Immunohistochemical localization of galectin-3 in the reproductive organs of the cow

The protein levels and immunohistochemical localization of galectin-3, which is a β-galactoside-binding protein, were studied in the cow reproductive organs. Using Western blot analysis, galectin-3 was detected at low levels in the ovary and oviduct, at moderate levels in the uterus, and at high levels in the cervix. Using immunohistochemistry, galectin-3 was immunolocalized in macrophages in the interstitium, in cells in the atretic follicles, and in luteal cells in the regressing corpus luteum, but not in the growing follicles in the ovary. In the oviduct, galectin-3 was detected in some macrophages in the lamina propria, submucosa and muscle layers, as well as in some cells in the covering epithelium. In the uterus, galectin-3 was immunolocalized in some epithelial cells and in some macrophages in the submucosa, but not in the endometrial glands at the non-pregnant stage. In the cervix, galectin-3 was immunolocalized in many mucus-secreting cells in the mucosa and in a few macrophages in the submucosa and muscle layers. Based on its localization, we postulate that galectin-3 in the covering epithelium is involved in the mucosal defense system, and that galectin-3-positive macrophages in all tissues are involved in either cell survival or death. In addition, galectin-3 plays an important role in the regression of follicles and the corpus luteum.