DIFFERENTIAL EXPRESSION OF 2 BETA-GALACTOSIDE-BINDING LECTINS IN THE REPRODUCTIVE TRACTS OF PREGNANT MICE

Two beta-galactoside-binding proteins were isolated from uteroplacenta l complexes of pregnant mice and identified as the S-Lac lectins galec tin-1 and galectin-3. The spatiotemporal pattern of appearance of thos e proteins was determined by immunocyt ochemistry. Galectin-1 was pres ent in all tissue compartments of the uterus except the luminal and gl andular epithelium. It was found in the uteri of animals from all prei mplantation stages of pregnancy, as well as in those from nonpregnant, ovariectomized, or sexually immature animals. After implantation of t he embryo, cells of the decidua basalis were labeled, as were granular metrial gland cells, all trophoblastic elements of the placenta, the myometrium, and nondecidualized endometrium. By contrast, there was li ttle evidence of galectin-3 in the uteri of nonpregnant animals or dur ing the preimplantation stages of pregnancy. However, immunoreactive m aterial was observed in endometrial cells of the primary decidual zone immediately after implantation and at later stages of pregnancy in th e decidua basalis, metrial gland, and all trophoblastic elements of th e placenta. There was no evidence of galectin-3 in the myometrium or n ondecidualized endometrium. After parturition, amounts of galectin-3 i n the endometrium and metrial triangle appeared to decrease as the imp lantation sites were resorbed. These data suggested that the function of galectin-1 is one of tissue maintenance, whereas the function of ga lectin-3 is related specifically to pregnancy.