Histochemical study of beta-glucuronidase in the rat uterus during implantation and pseudopregnancy.

On Day 5 of pregnancy and pseudopregnancy, beta-glucuronidase activity in pseudopregnant uteri and in the inter-implantation zones from pregnant animals was found mainly in stromal and glandular epithelial cells. The luminal epithelium also showed an intense enzyme-positive reaction, particularly in the apical regions of these cells. Blastocyst attachment was associated with marked depletion of beta-glucuronidase activity from epithelial cells lying adjacent to the blastocyst, suggesting a possible involvement of this lysosomal enzyme in the blastocyst-endometrium attachment reaction.