Publications by authors named "Masamichi Kurohmaru"

66 Publications

Di-n-butyl phthalate diminishes testicular steroidogenesis by blocking the hypothalamic-pituitary-testicular axis: relationship with germ cell apoptosis in Japanese quail.

Reprod Fertil Dev 2021 Mar;33(5):319-327

Laboratory of Veterinary Anatomy, Department of Veterinary Medicine, Okayama University of Science, Imabari, Ehime 794-8555, Japan; and Department of Veterinary Anatomy, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.

Although di-n-butyl phthalate (DBP) induces germ cell apoptosis, the underlying mechanism is not yet clear in quail. In this study, prepubertal quails were given a single dose of 500mg kg-1 DBP by gavage and were then killed 3, 6 and 24h after treatment. There was a significant reduction in intratesticular testosterone (ITT) concentrations and testicular steroidogenic enzyme mRNA expression and a significant increase in germ cell apoptosis in DBP-treated compared with control quails at all time points. Maximum apoptosis was detected 6h after treatment and the maximum reduction in testosterone concentrations was at 3h. To investigate whether DBP suppressed testicular steroidogenesis by affecting the hypothalamic-pituitary-testicular axis, we analysed pituitary LH subunit β (Lhb) mRNA expression and serum LH concentrations. At all time points, pituitary Lhb expression and serum LH concentrations were significantly decreased following DBP treatment. The present observations suggest the possibility that DBP blocked LH secretion from the hypothalamus and/or pituitary, thereby decreasing LH stimulation of Leydig cells and reducing ITT concentrations. DBP-induced decreases in ITT concentrations may cause changes to the physical structure of Sertoli cells, which, in turn, may induce germ cell apoptosis.
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http://dx.doi.org/10.1071/RD20150DOI Listing
March 2021

Low retinoic acid levels mediate regionalization of the Sertoli valve in the terminal segment of mouse seminiferous tubules.

Sci Rep 2021 Jan 13;11(1):1110. Epub 2021 Jan 13.

Department of Veterinary Anatomy, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.

In mammalian testes, undifferentiated spermatogonia (A) undergo differentiation in response to retinoic acid (RA), while their progenitor states are partially maintained by fibroblast growth factors (FGFs). Sertoli valve (SV) is a region located at the terminal end of seminiferous tubule (ST) adjacent to the rete testis (RT), where the high density of A is constitutively maintained with the absence of active spermatogenesis. However, the molecular and cellular characteristics of SV epithelia still remain unclear. In this study, we first identified the region-specific AKT phosphorylation in the SV Sertoli cells and demonstrated non-cell autonomous specialization of Sertoli cells in the SV region by performing a Sertoli cell ablation/replacement experiment. The expression of Fgf9 was detected in the RT epithelia, while the exogenous administration of FGF9 caused ectopic AKT phosphorylation in the Sertoli cells of convoluted ST. Furthermore, we revealed the SV region-specific expression of Cyp26a1, which encodes an RA-degrading enzyme, and demonstrated that the increased RA levels in the SV region disrupt its pool of A by inducing their differentiation. Taken together, RT-derived FGFs and low levels of RA signaling contribute to the non-cell-autonomous regionalization of the SV epithelia and its local maintenance of A in the SV region.
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http://dx.doi.org/10.1038/s41598-020-79987-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7806815PMC
January 2021

Postnatal testicular development and actin appearance in the seminiferous epithelium of the Habu, Trimeresurus flavoviridis.

Anat Histol Embryol 2021 Mar 26;50(2):417-421. Epub 2020 Oct 26.

Department of Veterinary Anatomy, The University of Tokyo, Tokyo, Japan.

The postnatal testicular development and actin distribution in the seminiferous epithelium were examined by light microscopy, using the testes of the Habu (Trimeresurus flavoviridis; snake) from 0-year-old to 3-year-old. At 0-year-old (about 1 month after birth), the testis was quite small in size, and the seminiferous epithelium was composed of only Sertoli cells and large spermatogonia. Actin immunoreactivity was observed in the peritubular myoid cells, but could not be detected in the seminiferous epithelium. At 1-year-old (about 10 months after birth), the testicular size increased to a great degree. In the seminiferous epithelium, spermatocytes newly appeared. Actin could still not be detected in the seminiferous epithelium. At 2-year-old (about 1 year and 10 months after birth), the testes continued to develop in size. In the seminiferous epithelium, elongate spermatids and round spermatids were frequently seen, in addition to Sertoli cells, spermatogonia and spermatocytes. Thus, active spermatogenesis was clearly recognized at this age. Moreover, the actin distribution in the seminiferous epithelium was observed at the site between Sertoli cells and spermatids, as well as that at adult stage. The immunoreactivity of actin in the peritubular myoid cells gradually increased from 0-year-old to 2-year-old. Conclusively, it seems likely that spermatogenesis in the Habu initiates at 2-year-old, accompanying with the appearance of actin in the seminiferous epithelium.
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http://dx.doi.org/10.1111/ahe.12628DOI Listing
March 2021

Species-specific and heterogeneous distribution of sialoglycoconjugates in the primary olfactory center of three species of Asian salamanders (Cynops).

Tissue Cell 2020 Dec 19;67:101428. Epub 2020 Aug 19.

Laboratory of Veterinary Anatomy, Faculty of Veterinary Medicine, Okayama University of Science, Imabari, Ehime, Japan.

Sialic acids (Sia) are terminal components of glycoconjugates that are involved in molecular and cellular interactions in the olfactory system. Diverse glycoconjugates are expressed in the salamander olfactory projection; however, their sialylation and the linkage of Sia to underlying sugars remain largely unknown. The present study aimed to determine the expression of Sia linked to galactose (Gal)-N-acetylglucosamine and N-acetylgalactosamine (GalNAc) in the olfactory bulbs of three species of salamanders using lectin binding. Abundant distribution of sialoglycoconjugates was observed in the salamander olfactory bulb by lectins, Sambucus sieboldiana (SSA) and Maackia amurensis (MAM). Moreover, SSA and MAM showed heterogeneous bindings in the primary olfactory projection of Cynops pyrrhogaster and C. orientalis. Lectin reactivities obviously decreased in all layers of the olfactory bulb after sialidase digestion, indicating selective binding to sialoglycoconjugates. Next, we examined the expression of the subterminal sugar residues, Gal and GalNAc, after terminal Sia removal. Desialylation in the olfactory bulb enhanced the reactivity of Jacalin and Vicia villosa (VVA) lectins that recognize Gal and GalNAc respectively. Together with the binding of SSA and MAM, Sia linked to Gal and GalNAc might be a major component of sialoglycoconjugates in the salamander olfactory projection.
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http://dx.doi.org/10.1016/j.tice.2020.101428DOI Listing
December 2020

Anatomical and histological characteristics of the hepatobiliary system in adult Sox17 heterozygote mice.

Anat Rec (Hoboken) 2020 12 2;303(12):3096-3107. Epub 2020 Jul 2.

Department of Veterinary Anatomy, The University of Tokyo, Tokyo, Japan.

Biliary atresia (BA) is a rare neonatal disease characterized by inflammation and obstruction of the extrahepatic bile ducts (EHBDs). The Sox17-haploinsufficient (Sox17 ) mouse is an animal model of BA that encompasses bile duct injury and subsequent BA-like inflammation by the neonatal stage. Most Sox17 neonates die soon after birth, but some Sox17 pups reach adulthood and have a normal life span, unlike human BA. However, the phenotype and BA-derived scars in the hepatobiliary organs of surviving Sox17 mice are unknown. Here, we examined the phenotypes of the hepatobiliary organs in post-weaning and young adult Sox17 mice. The results confirmed the significant reduction in liver weight, together with peripheral calcinosis and aberrant vasculature in the hepatic lobule, in surviving Sox17 mice as compared with their wild-type (WT) littermates. Such hepatic phenotypes may be sequelae of hepatobiliary damage at the fetal and neonatal stages, a notion supported by the slight, but significant, increases in the levels of serum markers of liver damage in adult Sox17 mice. The surviving Sox17 mice had a shorter gallbladder in which ectopic hepatic ducts were more frequent compared to WT mice. Also, the surviving Sox17 mice showed neither obstruction of the EHBDs nor atrophy or inflammation of hepatocytes or the intrahepatic ducts. These data suggest that some Sox17 pups with BA naturally escape lethality and recover from fetal hepatobiliary damages during the perinatal period, highlighting the usefulness of the in vivo model in understanding the hepatobiliary healing processes after surgical restoration of bile flow in human BA.
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http://dx.doi.org/10.1002/ar.24466DOI Listing
December 2020

Neurochemical characterization of mouse dorsal root ganglion neurons expressing organic cation transporter 2.

Neuroreport 2020 02;31(3):274-280

Department of Anatomy and Neurobiology, National Defense Medical College, Tokorozawa, Saitama, Japan.

Organic cation transporters (OCTs) are poly-specific carriers for endogenous and exogenous cationic compounds. These are widely distributed in the nervous system and mediate neuronal activities. As antineoplastic cationic drugs accumulate in the dorsal root ganglion (DRG), OCT function has been studied mainly in cultured DRG neurons. However, the histological distribution of OCTs in the DRG is unclear. This study investigated the localization of OCT2 (a member of OCTs) in mouse DRG neurons and determined their histochemical properties. OCT2 expression was found in about 20% of DRG neurons, which were small to medium size. OCT2-expressing neurons were labeled with markers for peptidergic nociceptive (substance P or calcitonin gene-related peptide) and tactile/proprioceptive (neurofilament 200 or tropomyosin receptor kinase B or C) neurons. OCT2 was also expressed in cholinergic DRG neurons identified by choline acetyltransferase promoter-derived Cre expression. In the spinal dorsal horn, OCT2 was distributed in superficial to deep laminae. OCT2 immunoreactivity was punctate in appearance and localized in the nerve terminals of sensory afferents with labeling of neurochemical markers. Our findings suggest that OCT2 as a low-affinity, high-capacity carrier may take up substrates including cationic neurotransmitters and drugs from the extracellular space around cell bodies in DRG neurons.
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http://dx.doi.org/10.1097/WNR.0000000000001416DOI Listing
February 2020

Characterization of glycoconjugates and sialic acid modification in the olfactory bulb of the Chinese fire-bellied newt (Cynops orientalis).

Anat Histol Embryol 2020 Mar 18;49(2):260-269. Epub 2019 Dec 18.

Laboratory of Veterinary Anatomy, Faculty of Veterinary Medicine, Okayama University of Science, Imabari, Japan.

Diverse glycoconjugates are expressed in the vertebrate olfactory bulb and serve as guidance cues for axons of nasal receptor neurons. Although the involvement of glycoconjugates in the segregation of the olfactory pathway has been suggested, it is poorly understood in salamanders. In this study, lectin histochemistry was used to determine glycoconjugate distribution in the olfactory bulb of the Chinese fire-bellied newt (Cynops orientalis). Succinylated wheat germ agglutinin (sWGA), Ricinus communis agglutinin-I and Lens culinaris agglutinin showed different bindings in the nerve fibre layer or glomerular layer, or both, between the main and accessory olfactory bulbs. We then investigated the lectin-binding pattern after the removal of terminal sialic acids using neuraminidase. Desialylation resulted in a change in the binding reactivities with seven lectins. Wheat germ agglutinin, sWGA, soybean agglutinin (SBA) and peanut agglutinin showed different degrees of binding between the main and accessory olfactory bulbs. In addition, SBA showed a heterogeneous labelling of glomeruli in the rostral region of the main olfactory bulb. Our results suggest that terminal sialic acids mask the heterogeneity of glycoconjugates in the olfactory bulb of C. orientalis.
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http://dx.doi.org/10.1111/ahe.12524DOI Listing
March 2020

Distribution of actin filaments in the seminiferous epithelium of the Habu, Trimeresurus flavoviridis.

Anat Histol Embryol 2019 Sep 7;48(5):505-507. Epub 2019 Aug 7.

Department of Veterinary Anatomy, The University of Tokyo, Tokyo, Japan.

The distribution of actin filaments was examined in the seminiferous epithelium of the Habu (Trimeresurus flavoviridis; snake), by transmission electron microscopy and fluorescence histochemistry. By transmission electron microscopy, actin filaments were clearly found only at the site between Sertoli cell and spermatid without a lattice-like structure. Fluorescence histochemistry showed a weak labelling of actin filaments in the seminiferous epithelium, whereas these findings seem to be common among reptiles, they are different from those in mammals. Additionally, the bundles of actin filaments adjacent to the plasma membrane of Sertoli cells, appeared in other reptiles, were not observed in the Habu.
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http://dx.doi.org/10.1111/ahe.12475DOI Listing
September 2019

Molecular and genetic characterization of partial masculinization in embryonic ovaries grafted into male nude mice.

PLoS One 2019 6;14(3):e0212367. Epub 2019 Mar 6.

Department of Veterinary Anatomy, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.

In most of mammalian embryos, gonadal sex differentiation occurs inside the maternal uterus before birth. In several fetal ovarian grafting experiments using male host mice, an experimental switch from the maternal intrauterine to male-host environment gradually induces partial masculinization of the grafted ovaries even under the wild-type genotype. However, either host-derived factors causing or molecular basis underlying this masculinization of the fetal ovaries are not clear. Here, we demonstrate that ectopic appearance of SOX9-positive Sertoli cell-like cells in grafted ovaries was mediated by the testosterone derived from the male host. Neither Sox8 nor Amh activity in the ovarian tissues is essential for such ectopic appearance of SOX9-positive cells. The transcriptome analyses of the grafted ovaries during this masculinization process showed early downregulation of pro-ovarian genes such as Irx3, Nr0b1/Dax1, Emx2, and Fez1/Lzts1 by days 7-10 post-transplantation, and subsequent upregulation of several pro-testis genes, such as Bhlhe40, Egr1/2, Nr4a2, and Zc3h12c by day 20, leading to a partial sex reversal with altered expression profiles in one-third of the total numbers of the sex-dimorphic pre-granulosa and Sertoli cell-specific genes at 12.5 dpc. Our data imply that the paternal testosterone exposure is partially responsible for the sex-reversal expression profiles of certain pro-ovarian and pro-testis genes in the fetal ovaries in a temporally dependent manner.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0212367PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6402656PMC
November 2019

CRISPR/Cas9-mediated knock-in of the murine Y chromosomal Sry gene.

J Reprod Dev 2018 Jun 14;64(3):283-287. Epub 2018 Apr 14.

Department of Veterinary Anatomy, The University of Tokyo, Tokyo 113-8657, Japan.

Mammalian zygote-mediated genome editing via the clustered regularly interspaced short palindromic repeats/CRISPR-associated endonuclease 9 (CRISPR/Cas9) system is widely used to generate genome-modified animals. This system allows for the production of loss-of-function mutations in various Y chromosome genes, including Sry, in mice. Here, we report the establishment of a CRISPR-Cas9-mediated knock-in line of Flag-tag sequences into the Sry locus at the C-terminal coding end of the Y chromosome (Y). In the F1 and successive generations, all male pups carrying the Y chromosome had normal testis differentiation and proper spermatogenesis at maturity, enabling complete fertility and the production of viable offspring. To our knowledge, this study is the first to produce a stable Sry knock-in line at the C-terminal region, highlighting a novel approach for examining the significance of amino acid changes at the naive Sry locus in mammals.
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http://dx.doi.org/10.1262/jrd.2017-161DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6021606PMC
June 2018

Sox17 is essential for proper formation of the marginal zone of extraembryonic endoderm adjacent to a developing mouse placental disk.

Biol Reprod 2018 09;99(3):578-589

Department of Veterinary Anatomy, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.

In mouse conceptus, two yolk-sac membranes, the parietal endoderm (PE) and visceral endoderm (VE), are involved in protecting and nourishing early-somite-stage embryos prior to the establishment of placental circulation. Both PE and VE membranes are tightly anchored to the marginal edge of the developing placental disk, in which the extraembryonic endoderm (marginal zone endoderm: ME) shows the typical flat epithelial morphology intermediate between those of PE and VE in vivo. However, the molecular characteristics and functions of the ME in mouse placentation remain unclear. Here, we show that SOX17, not SOX7, is continuously expressed in the ME cells, whereas both SOX17 and SOX7 are coexpressed in PE cells, by at least 10.5 days postconception. The Sox17-null conceptus, but not the Sox7-null one, showed the ectopic appearance of squamous VE-like epithelial cells in the presumptive ME region, together with reduced cell density and aberrant morphology of PE cells. Such aberrant ME formation in the Sox17-null extraembryonic endoderm was not rescued by the chimeric embryo replaced with the wild-type gut endoderm by the injection of wild-type ES cells into the Sox17-null blastocyst, suggesting the cell autonomous defects in the extraembryonic endoderm of Sox17-null concepti. These findings provide direct evidence of the crucial roles of SOX17 in proper formation and maintenance of the ME region, highlighting a novel entry point to understand the in vivo VE-to-PE transition in the marginal edge of developing placenta.
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http://dx.doi.org/10.1093/biolre/ioy079DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6692860PMC
September 2018

Regionally distinct patterns of STAT3 phosphorylation in the seminiferous epithelia of mouse testes.

Mol Reprod Dev 2018 03 1;85(3):262-270. Epub 2018 Mar 1.

Department of Veterinary Anatomy, The University of Tokyo, Yayoi, Tokyo, Japan.

In mouse testes, Sertoli cells support the continuous process of spermatogenesis, which is dependent on seminiferous epithelial cycles along the longitudinal axis of the seminiferous tubule. Sertoli cell function is modulated partly by local cytokines and/or growth factors derived from adjacent tissues such as blood vessels, macrophages, rete testis, etc. However, the spatial activation patterns by local signals in vivo remain unclear. In this study, we focused on Signal Transducers and Activators of Transcription (STAT) signaling in Sertoli cells, because STAT is a major crucial cytokine transducer for somatic cyst cell regulation in Drosophila testis niches. In mouse testes, STAT3 was ubiquitously expressed in Sertoli cells throughout the seminiferous tubules. Phosphorylated STAT3 (p-STAT3) was predominantly observed in the Sertoli cells within the valve-like structure adjacent to the rete testis (i.e., the Sertoli valve [SV]) in the terminal segment of the proximal seminiferous tubules. In the distal seminiferous tubules with active spermatogenesis, most Sertoli cells were negative for anti-p-STAT3 staining. Albeit rarely, a small patch of several p-STAT3-positive Sertoli cells was detected frequently in seminiferous epithelial cycle stages I-VI. Such p-STAT3-positive ratios in the convoluted seminiferous epithelia were significantly increased in germ cell-less testes than in the wild-type testes, but with considerably lower ratios than in the SV region. These findings imply that regionally distinct patterns of STAT3 phosphorylation in the Sertoli cells depend on either location or spermatogenic activity in normal healthy testes in vivo, highlighting a novel entry point to understanding STAT signaling in mammalian spermatogenesis.
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http://dx.doi.org/10.1002/mrd.22962DOI Listing
March 2018

Anatomy and development of the extrahepatic biliary system in mouse and rat: a perspective on the evolutionary loss of the gallbladder.

J Anat 2018 Jan 10;232(1):134-145. Epub 2017 Oct 10.

Laboratory of Veterinary Anatomy, The University of Tokyo, Tokyo, Japan.

The gallbladder is the hepatobiliary organ for storing and secreting bile fluid, and is a synapomorphy of extant vertebrates. However, this organ has been frequently lost in several lineages of birds and mammals, including rodents. Although it is known as the traditional problem, the differences in development between animals with and without gallbladders are not well understood. To address this research gap, we compared the anatomy and development of the hepatobiliary systems in mice (gallbladder is present) and rats (gallbladder is absent). Anatomically, almost all parts of the hepatobiliary system of rats are topographically the same as those of mice, but rats have lost the gallbladder and cystic duct completely. During morphogenesis, the gallbladder-cystic duct domain (Gb-Cd domain) and its primordium, the biliary bud, do not develop in the rat. In the early stages, SOX17, a master regulator of gallbladder formation, is positive in the murine biliary bud epithelium, as seen in other vertebrates with a gallbladder, but there is no SOX17-positive domain in the rat hepatobiliary primordia. These findings suggest that the evolutionary loss of the Gb-Cd domain should be translated simply as the absence of a biliary bud at an early stage, which may correlate with alterations in regulatory genes, such as Sox17, in the rat. A SOX17-positive biliary bud is clearly definable as a developmental module that may be involved in the frequent loss of gallbladder in mammals.
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http://dx.doi.org/10.1111/joa.12707DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5735046PMC
January 2018

Spermatogonial deubiquitinase USP9X is essential for proper spermatogenesis in mice.

Reproduction 2017 08 30;154(2):135-143. Epub 2017 May 30.

Department of Veterinary AnatomyThe University of Tokyo, Bunkyo-ku, Tokyo, Japan

USP9X (ubiquitin-specific peptidase 9, X chromosome) is the mammalian orthologue of deubiquitinase fat facets that was previously shown to regulate the maintenance of the germ cell lineage partially through stabilizing Vasa, one of the widely conserved factors crucial for gametogenesis. Here, we demonstrate that USP9X is expressed in the gonocytes and spermatogonia in mouse testes from newborn to adult stages. By using mice, germ cell-specific conditional deletion of from the embryonic stage showed no abnormality in the developing testes by 1 week and no appreciable defects in the undifferentiated and differentiating spermatogonia at postnatal and adult stages. Interestingly, after 2 weeks, -null spermatogenic cells underwent apoptotic cell death at the early spermatocyte stage, and then, caused subsequent aberrant spermiogenesis, which resulted in a complete infertility of conditional knockout male mice. These data provide the first evidence of the crucial role of the spermatogonial USP9X during transition from the mitotic to meiotic phases and/or maintenance of early meiotic phase in conditional knockout testes.
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http://dx.doi.org/10.1530/REP-17-0184DOI Listing
August 2017

Embryonic cholecystitis and defective gallbladder contraction in the -haploinsufficient mouse model of biliary atresia.

Development 2017 05 21;144(10):1906-1917. Epub 2017 Apr 21.

Department of Veterinary Anatomy, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan

The gallbladder excretes cytotoxic bile acids into the duodenum through the cystic duct and common bile duct system. haploinsufficiency causes biliary atresia-like phenotypes and hepatitis in late organogenesis mouse embryos, but the molecular and cellular mechanisms underlying this remain unclear. In this study, transcriptomic analyses revealed the early onset of cholecystitis in embryos, together with the appearance of ectopic cystic duct-like epithelia in their gallbladders. The embryonic hepatitis showed positive correlations with the severity of cholecystitis in individual embryos. Embryonic hepatitis could be induced by conditional deletion of in the primordial gallbladder epithelia but not in fetal liver hepatoblasts. The gallbladder also showed a drastic reduction in sonic hedgehog expression, leading to aberrant smooth muscle formation and defective contraction of the fetal gallbladder. The defective gallbladder contraction positively correlated with the severity of embryonic hepatitis in embryos, suggesting a potential contribution of embryonic cholecystitis and fetal gallbladder contraction in the early pathogenesis of congenital biliary atresia.
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http://dx.doi.org/10.1242/dev.147512DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5450840PMC
May 2017

Defects in the first wave of folliculogenesis in mouse XO ovaries.

J Reprod Dev 2017 Jun 10;63(3):333-338. Epub 2017 Apr 10.

Department of Veterinary Anatomy, The University of Tokyo, Tokyo 113-8657, Japan.

In mouse ovaries, the first wave of folliculogenesis perinatally starts near the medullary region, which directs the initial round of follicular growth soon after birth. At the same time, cortical primordial follicles start forming in the ovarian surface region, and then some are cyclically recruited for the second and subsequent rounds of follicular growth. Recent studies suggest different dynamics between the first and subsequent waves of follicular growth in postnatal ovaries. However, the phenotypic differences between these phases remain unclear. Here, we show direct evidence that XO female mice, a murine model for Turner Syndrome, lack the first wave of folliculogenesis. Our histopathological analyses of XX and XO littermates revealed a lack of anti-Müllerian hormone (AMH)-positive primary follicles in the XO ovaries by 4 days post partum (dpp). This loss of first follicles was also confirmed by histological bioassay for SRY-dependent SOX9 inducibility, a specific marker for the first follicular granulosa cells. In contrast, cortical primordial follicles formed properly in XO ovaries, and some of them formed primary and secondary follicles in the subcortical region by 7 dpp. They rapidly developed into late antral follicles, showing similarities to XX littermate ovaries by 21 dpp. These results suggest distinct X-monosomy effects between the first and subsequent waves of follicular growth, highlighting the high susceptibility to elimination of XO oocytes in the first wave of mammalian folliculogenesis.
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http://dx.doi.org/10.1262/jrd.2017-033DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5481637PMC
June 2017

In vivo dynamics of GFRα1-positive spermatogonia stimulated by GDNF signals using a bead transplantation assay.

Biochem Biophys Res Commun 2016 08 31;476(4):546-552. Epub 2016 May 31.

Department of Veterinary Anatomy, The University of Tokyo, Yayoi, Tokyo, 113-8657, Japan. Electronic address:

In mouse testes, spermatogonial stem cells (SSCs), a subpopulation of GFRα1 (GDNF family receptor-α1)-positive spermatogonia, are widely distributed along the convoluted seminiferous tubules. The proliferation and differentiation of the SSCs are regulated in part by local expression of GDNF (glial cell-derived neurotorphic factor), one of major niche factors for SSCs. However, the in vivo dynamics of the GDNF-stimulated GFRα1-positive spermatogonia remains unclear. Here, we developed a simple method for transplanting DiI-labeled and GDNF-soaked beads into the mouse testicular interstitium. By using this method, we examined the dynamics of GFRα1-positive spermatogonia in the tubular walls close to the transplanted GDNF-soaked beads. The bead-derived GDNF signals were able to induce the stratified aggregate formation of GFRα1-positive undifferentiated spermatogonia by day 3 post-transplantation. Each aggregate consisted of tightly compacted Asingle and marginal Apaired-Aaligned GFRα1-positive spermatogonia and was surrounded by Aaligned GFRα1-negative spermatogonia at more advanced stages. These data not only provide in vivo evidence for the inductive roles of GDNF in forming a rapid aggregation of GFRα1-positive spermatogonia but also indicate the usefulness of this in vivo assay system of various growth factors for the stem/progenitor spermatogonia in mammalian spermatogenesis.
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http://dx.doi.org/10.1016/j.bbrc.2016.05.160DOI Listing
August 2016

Butylbenzyl phthalate induces spermatogenic cell apoptosis in prepubertal rats.

Tissue Cell 2016 Feb 5;48(1):35-42. Epub 2015 Dec 5.

Department of Veterinary Anatomy, Graduate School of Agricultural & Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.

Butylbenzyl phthalate (BBP), a suspected endocrine disruptor, adversely affects male reproductive function. In this study, morphological alterations of prepubertal rat testes caused by single administration of BBP, were examined by light microscopy. Three-week-old male rats were given a single dose of 500 mg/kg BBP by oral gavage and sacrificed at 3, 12, and 24 h after administration. Histopathological examination revealed progressive detachment and sloughing of spermatogenic cells into the lumen, and a significant increase in the number of TUNEL-positive (apoptotic) spermatogenic cells in the treated groups, compared to the control. Semithin sections confirmed the apoptotic cells by their prominent basophilia, condensed chromatin, and shrunken cytoplasm, hallmarks of apoptotic cell death. Immunohistochemistry identified disruption of Sertoli cell vimentin and actin filaments in the treated groups. To elucidate the recovery effects of BBP, rats were treated in the same way and were sacrificed at D1-12h after administration. The apoptotic index returned to normal at D9. While, the testes revealed lower weight gain until D12. These results show for the first time that BBP induces collapse of vimentin filaments in Sertoli cells which may lead to disruption of Sertoli-spermatogenic cell physical interaction and induces spermatogenic cell apoptosis.
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http://dx.doi.org/10.1016/j.tice.2015.12.001DOI Listing
February 2016

Anatomy of the Murine Hepatobiliary System: A Whole-Organ-Level Analysis Using a Transparency Method.

Anat Rec (Hoboken) 2016 Feb 2;299(2):161-72. Epub 2015 Dec 2.

Laboratory of Veterinary Anatomy, The University of Tokyo, Tokyo, 113 8657, Japan.

The biliary tract is a well-branched ductal structure that exhibits great variation in morphology among vertebrates. Its function is maintained by complex constructions of blood vessels, nerves, and smooth muscles, the so-called hepatobiliary system. Although the mouse (Mus musculus) has been used as a model organism for humans, the morphology of its hepatobiliary system has not been well documented at the topographical level, mostly because of its small size and complexity. To reconcile this, we conducted whole-mount anatomical descriptions of the murine extrahepatic biliary tracts with related blood vessels, nerves, and smooth muscles using a recently developed transparentizing method, CUBIC. Several major differences from humans were found in mice: (1) among the biliary arteries, the arteria gastrica sinistra accessoria was commonly found, which rarely appears in humans; (2) the sphincter muscle in the choledochoduodenal junction is unseparated from the duodenal muscle; (3) the pancreatic duct opens to the bile duct without any sphincter muscles because of its distance from the duodenum. This state is identical to a human congenital malformation, an anomalous arrangement of pancreaticobiliary ducts. However, other parts of the murine hepatobiliary system (such as the branching patterns of the biliary tract, blood vessels, and nerves) presented the same patterns as humans and other mammals topologically. Thus, the mouse is useful as an experimental model for studying the human hepatobiliary system.
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http://dx.doi.org/10.1002/ar.23287DOI Listing
February 2016

A Niche for GFRα1-Positive Spermatogonia in the Terminal Segments of the Seminiferous Tubules in Hamster Testes.

Stem Cells 2015 Sep 23;33(9):2811-24. Epub 2015 Jun 23.

Department of Veterinary Anatomy, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan.

In invertebrate species such as flies and nematodes, germline stem cells are maintained in a niche environment, which is restricted to the terminal end of the tubular structure in the gonads. In mice, spermatogonial stem cells (SSCs), a subpopulation of Asingle GFRα1 (glial cell line-derived neurotrophic factor [GDNF] family receptor-α1)-positive spermatogonia, are widely distributed along the longitudinal axis in the convoluted seminiferous tubules, preferentially juxtaposed to the interstitial vasculature. However, whether this area is the only SSC niche is not known. In this study, we identified a valve-like terminal segment of the seminiferous tubules, the Sertoli valve (SV), adjacent to the rete testis as another niche for GFRα1-positive spermatogonia in hamsters. Here, we show that the SV epithelium is composed of the modified Sertoli cells that are still capable of proliferation and missing most spermatogenic activities in the adult stage. The SV epithelium constitutively expresses GDNF, a major niche factor for SSCs, and supports the stable proliferation and selective maintenance of an Asingle subpopulation of GFRα1-positive spermatogonia in hamsters. The SV region of hamster seminiferous tubules has features that are similar to the stem cell niche in invertebrate gonads. Therefore, we propose that the SV may be a novel niche for Asingle GFRá1-positive spermatogonia potentially including a SSC population, at the terminal segments of the seminiferous tubules in hamsters.
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http://dx.doi.org/10.1002/stem.2065DOI Listing
September 2015

Fate mapping of gallbladder progenitors in posteroventral foregut endoderm of mouse early somite-stage embryos.

J Vet Med Sci 2015 May 7;77(5):587-91. Epub 2015 Jan 7.

Department of Veterinary Anatomy, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.

In early embryogenesis, the posteroventral foregut endoderm gives rise to the budding endodermal organs including the liver, ventral pancreas and gallbladder during early somitogenesis. Despite the detailed fate maps of the liver and pancreatic progenitors in the mouse foregut endoderm, the exact location of the gallbladder progenitors remains unclear. In this study, we performed a DiI fate-mapping analysis using whole-embryo cultures of mouse early somite-stage embryos. Here, we show that the majority of gallbladder progenitors in 9-11-somite-stage embryos are located in the lateral-most domain of the foregut endoderm at the first intersomite junction level along the anteroposterior axis. This definition of their location highlights a novel entry point to understanding of the molecular mechanisms of initial specification of the gallbladder.
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http://dx.doi.org/10.1292/jvms.14-0635DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4478739PMC
May 2015

A novel Amh-Treck transgenic mouse line allows toxin-dependent loss of supporting cells in gonads.

Reproduction 2014 Dec 11;148(6):H1-9. Epub 2014 Sep 11.

Department of Veterinary AnatomyThe University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, JapanDepartment of Experimental Animal Model for Human DiseaseCenter for Experimental Animals, Tokyo Medical and Dental University, Yushima, Bunkyo-ku, Tokyo 113-8510, JapanGraduate School of Biological SciencesNara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara 630-0192, JapanINSERM U1133BFA, University Paris VII, 75205 Paris Cedex 13, France

Cell ablation technology is useful for studying specific cell lineages in a developing organ in vivo. Herein, we established a novel anti-Müllerian hormone (AMH)-toxin receptor-mediated cell knockout (Treck) mouse line, in which the diphtheria toxin (DT) receptor was specifically activated in Sertoli and granulosa cells in postnatal testes and ovaries respectively. In the postnatal testes of Amh-Treck transgenic (Tg) male mice, DT injection induced a specific loss of the Sertoli cells in a dose-dependent manner, as well as the specific degeneration of granulosa cells in the primary and secondary follicles caused by DT injection in Tg females. In the testes with depletion of Sertoli cell, germ cells appeared to survive for only several days after DT treatment and rapidly underwent cell degeneration, which led to the accumulation of a large amount of cell debris within the seminiferous tubules by day 10 after DT treatment. Transplantation of exogenous healthy Sertoli cells following DT treatment rescued the germ cell loss in the transplantation sites of the seminiferous epithelia, leading to a partial recovery of the spermatogenesis. These results provide not only in vivo evidence of the crucial role of Sertoli cells in the maintenance of germ cells, but also show that the Amh-Treck Tg line is a useful in vivo model of the function of the supporting cell lineage in developing mammalian gonads.
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http://dx.doi.org/10.1530/REP-14-0171DOI Listing
December 2014

Disruption of Sertoli cell vimentin filaments in prepubertal rats: an acute effect of butylparaben in vivo and in vitro.

Acta Histochem 2014 Jun 17;116(5):682-7. Epub 2014 Jan 17.

Department of Veterinary Anatomy, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.

Parabens are p-hydroxybenzoic acid ester compounds widely used as preservatives in foods, cosmetics, toiletries and pharmaceuticals. We have recently shown that butylparaben induces spermatogenic cell apoptosis in prepubertal rats. We have conducted the present study for further information. Three-week-old male Sprague-Dawley rats (n=8) were given a single oral dose of 1,000 mg/kg butylparaben. The rats were sacrificed under anesthesia at 3, 6 and 24h after administration and their testes were collected for histopathological and immunohistochemical examination. Results showed a gradual collapse of Sertoli cell vimentin filaments and decreased actin staining intensity without accompanying changes in the pattern of tubulin expression, while spermatogenic cells became separated from the basement membrane and sloughed into the lumen in the butylparaben-treated rats, compared to the controls. To determine the direct effects of butylparaben on Sertoli cells, primary Sertoli cell cultures with and without butylparaben treatment were examined. Toluidine blue staining in butylparaben treated-cultured Sertoli cells showed an increased number and size of vacuoles in their cytoplasm. In agreement with the in vivo experiment, the in vitro study also clearly demonstrated disruption of vimentin filaments in Sertoli cells after butylparaben treatment. Considering both our present and previous reports, we can speculate that butylparaben-induced disruption of Sertoli cell vimentin filaments may lead to precocious release of spermatogenic cells from underlying Sertoli cells, and the released cells may undergo apoptosis owing to loss of support provided by the Sertoli cells.
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http://dx.doi.org/10.1016/j.acthis.2013.12.006DOI Listing
June 2014

Single administration of butylparaben induces spermatogenic cell apoptosis in prepubertal rats.

Acta Histochem 2014 Apr 13;116(3):474-80. Epub 2013 Nov 13.

Department of Veterinary Anatomy, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan. Electronic address:

Parabens are p-hydroxybenzoic acid ester compounds widely used as preservatives in foods, cosmetics, toiletries and pharmaceuticals. Some parabens, including butylparaben, exert an estrogenic activity as determined by in vitro estrogen receptor assay and in vivo uterotrophic assay, and adversely affect endocrine secretion and male reproductive function. We conducted a research study to evaluate the acute effects of butylparaben on testicular tissues of prepubertal rats. Three-week-old male rats (n=8) were given a single dose of 1000mg/kg butylparaben. The rats were sacrificed under anesthesia at 3, 6 and 24h after administration, and their testes were collected for histopathological examination. The study revealed progressive detachment and sloughing of spermatogenic cells into the lumen of the seminiferous tubules at 3h, and this effect was enhanced at 6h after administration. Thin seminiferous epithelia and wide tubular lumina were seen at 24h in the butylparaben-treated group, compared to the control. In order to clarify whether sloughed spermatogenic cells underwent apoptosis, TUNEL assay was carried out. We found a significant increase in the number of apoptotic spermatogenic cells in all the treated groups, compared to the controls and a maximal number of apoptotic cells were detected at 6h after administration. In semithin sections, apoptotic cells were easily detected by their prominent basophilia and condensed chromatin, mainly found in spermatocytes. Ultrastructurally, the condensed chromatin and shrunken cytoplasm and nucleus, hallmarks of apoptotic cell death, were observed in butylparaben-treated groups. These observations lead us to postulate that butylparaben, similar to other estrogenic compounds, also induces spermatogenic cell apoptosis.
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http://dx.doi.org/10.1016/j.acthis.2013.10.006DOI Listing
April 2014

Heterogeneity in sexual bipotentiality and plasticity of granulosa cells in developing mouse ovaries.

J Cell Sci 2013 Jul 23;126(Pt 13):2834-44. Epub 2013 Apr 23.

Department of Veterinary Anatomy, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.

In mammalian sex determination, SRY directly upregulates the expression of SOX9, the master regulatory transcription factor in Sertoli cell differentiation, leading to testis formation. Without SRY action, the bipotential gonadal cells become pre-granulosa cells, which results in ovarian follicle development. When, where and how pre-granulosa cells are determined to differentiate into developing ovaries, however, remains unclear. By monitoring SRY-dependent SOX9 inducibility (SDSI) in an Sry-inducible mouse system, we were able to identify spatiotemporal changes in the sexual bipotentiality/plasticity of ovarian somatic cells throughout life. The early pre-granulosa cells maintain the SDSI until 11.5 d.p.c., after which most pre-granulosa cells rapidly lose this ability by 12.0 d.p.c. Unexpectedly, we found a subpopulation of the pre-granulosa cells near the mesonephric tissue that continuously retains SDSI throughout fetal and early postnatal stages. After birth, these SDSI-positive pre-granulosa cells contribute to the initial round of folliculogenesis by the secondary follicle stage. In experimental sex reversal of 13.5-d.p.c. ovaries grafted into adult male nude mice, the differentiated granulosa cells re-acquire the SDSI before other signs of masculinization. Our data provide direct evidence of an unexpectedly high sexual heterogeneity of granulosa cells in developing mouse ovaries in a stage- and region-specific manner. Discovery of such sexually bipotential granulosa cells provides a novel entry point to the understanding of masculinization in various cases of XX disorders of sexual development in mammalian ovaries.
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http://dx.doi.org/10.1242/jcs.122663DOI Listing
July 2013

Sox17 haploinsufficiency results in perinatal biliary atresia and hepatitis in C57BL/6 background mice.

Development 2013 Feb;140(3):639-48

Department of Veterinary Anatomy, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.

Congenital biliary atresia is an incurable disease of newborn infants, of unknown genetic causes, that results in congenital deformation of the gallbladder and biliary duct system. Here, we show that during mouse organogenesis, insufficient SOX17 expression in the gallbladder and bile duct epithelia results in congenital biliary atresia and subsequent acute 'embryonic hepatitis', leading to perinatal death in ~95% of the Sox17 heterozygote neonates in C57BL/6 (B6) background mice. During gallbladder and bile duct development, Sox17 was expressed at the distal edge of the gallbladder primordium. In the Sox17(+/-) B6 embryos, gallbladder epithelia were hypoplastic, and some were detached from the luminal wall, leading to bile duct stenosis or atresia. The shredding of the gallbladder epithelia is probably caused by cell-autonomous defects in proliferation and maintenance of the Sox17(+/-) gallbladder/bile duct epithelia. Our results suggest that Sox17 plays a dosage-dependent function in the morphogenesis and maturation of gallbladder and bile duct epithelia during the late-organogenic stages, highlighting a novel entry point to the understanding of the etiology and pathogenesis of human congenital biliary atresia.
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http://dx.doi.org/10.1242/dev.086702DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3561787PMC
February 2013

Evidence for almost complete sex-reversal in bovine freemartin gonads: formation of seminiferous tubule-like structures and transdifferentiation into typical testicular cell types.

J Reprod Dev 2012 20;58(6):654-60. Epub 2012 Jul 20.

Department of Veterinary Anatomy, The University of Tokyo, Tokyo 113-8657, Japan.

During mammalian sex determination of XY fetuses, SRY induces SOX9 in Sertoli cells, resulting in formation of testes with seminiferous tubules, interstitial Leydig cells and peritubular myoid cells. Meanwhile XX fetuses without SRY develop ovaries. In cattle, most XX heifers born with a male twin, so-called freemartins, develop nonfunctioning ovaries and genitalia with an intersex phenotype. Interestingly, freemartins sometimes develop highly masculinized gonads with seminiferous tubule-like structures despite the absence of SRY. However, in these cases, the degree of masculinization in each gonadal somatic cell type is unclear. Here, we report a rare case of a freemartin Japanese black calf with almost complete XX sexreversal. Gross anatomical analysis of this calf revealed the presence of a pair of small testis-like gonads with rudimentary epididymides, in addition to highly masculinized genitalia including a pampiniform plexus, scrotum and vesicular gland. Histological and immunohistochemical analyses of these masculinized gonads revealed well-defined seminiferous tubule-like structures throughout the whole gonadal parenchyma. In epithelia of these tubules, SOX9-positive supporting cells (i.e., Sertoli cells) were found to be arranged regularly along the bases of tubules, and they were also positive for GDNF, one of the major factors for spermatogenesis. 3β-HSD-positive cells (i.e., Leydig cells) and SMA-positive peritubular myoid cells were also identified around tubules. Therefore, for the first time, we found the transdifferentiation of ovarian somatic cells into all testicular somatic cell types in the XX freemartin gonads. These data strongly support the idea of a high sexual plasticity in the ovarian somatic cells of mammalian gonads.
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http://dx.doi.org/10.1262/jrd.2012-070DOI Listing
May 2013

Dynamics of GFRα1-positive spermatogonia at the early stages of colonization in the recipient testes of W/Wν male mice.

Dev Dyn 2012 Aug 9;241(8):1374-84. Epub 2012 Jul 9.

Department of Veterinary Anatomy, The University of Tokyo, Tokyo, Japan.

Background: The spermatogonial transplantation experiment can be used as an unequivocal detection assay of spermatogenic stem cells (SSCs) in both a qualitative and quantitative manner, based on their regenerative capacity. In this study, the proliferative patterns and kinetics of donor-derived GFRα1-positive spermatogonia containing potential SSCs were examined during early colonization following spermatogonial transplantation.

Results: Donor-derived GFRα1-positive cells frequently formed several aggregates of A(al(aligned)) /morula-like structures in a single spermatogenic cell patch before and on day 14 post-transplant, indicating a possible involvement in the formation of a stable spermatogenic colony at 21 days post-transplant. The appearance of these A(al) /morula-like aggregates is positively correlated with regional, high-level expression of immunoreactive GDNF signals, a ligand for GFRα1, associated with colony expansion.

Conclusions: These data raise the hypothesis that regional GDNF signals regulate the balance between donor-derived A(al) -like cell aggregates and their differentiation in each small patch, which subsequently leads to further selection of survival colonies at later stages.
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http://dx.doi.org/10.1002/dvdy.23824DOI Listing
August 2012

Cyclical and patch-like GDNF distribution along the basal surface of Sertoli cells in mouse and hamster testes.

PLoS One 2011 9;6(12):e28367. Epub 2011 Dec 9.

Department of Veterinary Anatomy, The University of Tokyo, Tokyo, Japan.

Background And Aims: In mammalian spermatogenesis, glial cell line-derived neurotrophic factor (GDNF) is one of the major Sertoli cell-derived factors which regulates the maintenance of undifferentiated spermatogonia including spermatogonial stem cells (SSCs) through GDNF family receptor α1 (GFRα1). It remains unclear as to when, where and how GDNF molecules are produced and exposed to the GFRα1-positive spermatogonia in vivo.

Methodology And Principal Findings: Here we show the cyclical and patch-like distribution of immunoreactive GDNF-positive signals and their close co-localization with a subpopulation of GFRα1-positive spermatogonia along the basal surface of Sertoli cells in mice and hamsters. Anti-GDNF section immunostaining revealed that GDNF-positive signals are mainly cytoplasmic and observed specifically in the Sertoli cells in a species-specific as well as a seminiferous cycle- and spermatogenic activity-dependent manner. In contrast to the ubiquitous GDNF signals in mouse testes, high levels of its signals were cyclically observed in hamster testes prior to spermiation. Whole-mount anti-GDNF staining of the seminiferous tubules successfully visualized the cyclical and patch-like extracellular distribution of GDNF-positive granular deposits along the basal surface of Sertoli cells in both species. Double-staining of GDNF and GFRα1 demonstrated the close co-localization of GDNF deposits and a subpopulation of GFRα1-positive spermatogonia. In both species, GFRα1-positive cells showed a slender bipolar shape as well as a tendency for increased cell numbers in the GDNF-enriched area, as compared with those in the GDNF-low/negative area of the seminiferous tubules.

Conclusion/significance: Our data provide direct evidence of regionally defined patch-like GDNF-positive signal site in which GFRα1-positive spermatogonia possibly interact with GDNF in the basal compartment of the seminiferous tubules.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0028367PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3235125PMC
April 2012

Effects of di-iso-butyl phthalate on testes of prepubertal rats and mice.

Okajimas Folia Anat Jpn 2010 Feb;86(4):129-36

Department of Veterinary Anatomy, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.

Di-iso-butyl phthalate (DiBP), a special plasticizer, is used as a substitute for di(n-butyl) phthalate (DBP). The effects of DiBP on testes in prepubertal rodents still remain to be obscure. Testicular toxicity of DiBP was investigated in 21-day-old Sprague-Dawley rats and C57BL/6N mice, using with in situ TUNEL method. For an acute exposure experiment, animals were once given DiBP at various concentrations by oral gavage. For a subchronic exposure experiment, they were daily given DiBP at various concentrations for consecutive 7 days. Controls were treated with corn oil under the same condition. For a recovery experiment, rats were once given DiBP (1000 mg/kg), and were sacrificed at day 1 to 8 after administration. Furthermore, the disorder of vimentin filaments in Sertoli cells after daily administration of DiBP (500 mg/kg) for consecutive 7 days in rats also identified by immunohistochemistry using anti-vimentin antibody. As a result, the present study demonstrated that DiBP can induce testicular atrophy in rats due to the increase of TUNEL-positive spermatogenic cells in both acute and subchronic exposure experiments. At the same time, the disorder of vimentin filaments in Sertoli cells was recognized. However, no such damages could be found in mouse testis. For the recovery experiment, the testis weight and testicular morphology returned to normal at day 6 after administration. In conclusion, the present study indicates that DiBP causes the significant increase of TUNEL-positive spermatogenic cells and the disorder of vimentin filaments in Sertoli cells in rats and that DiBP shows a species-specific toxicity.
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http://dx.doi.org/10.2535/ofaj.86.129DOI Listing
February 2010