Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, Texas 77030, USA.
Leukemia inhibitory factor (LIF) has been shown to play an important role in the implantation of mouse blastocysts. The present study was designed to investigate the changes of LIF protein, LIF receptor, and gp130 in the mouse uterus during the early pregnancy. LIF protein and LIF receptor were at high levels in the mouse uterus near the time of ovulation and on day 4 of pregnancy. gp130 was highest on days 3 and 4 of pregnancy. Both LIF receptor and gp130 showed strong staining in the stroma of the day 5 uterus, at a time when LIF protein was low. The presence of LIF receptor and gp130 in the luminal epithelium on day 4 and in the stroma on day 5 may indicate the site of the high affinity LIF receptor. The coexistence of a high level of LIF protein, LIF receptor, and gp130 in the day 4 uterus is consistent with the previously observed high level of uterine LIF mRNA on the same day and the importance of LIF for the blastocyst implantation in mouse.