Problem: During early pregnancy in mice, there is recruitment of specific immune cells, remodeling of the endometrium, cell differentiation and synthesis of new molecules.
Method of study: Immunohistochemistry was used to determine the distribution of perlecan and syndecan-4 in the uteri before and after embryo implantation.
Results: During pre-implantation, perlecan was identified in basement membranes and extracellular spaces of the endometrial stroma. In contrast, expression of syndecan-4 was quite weak. In the peri-implantation period, perlecan remained in the basement membranes, and it was no longer observed in the stroma and it was identified in the embryonic cells. On day 4 of pregnancy, syndecan-4 increased in the fibroblasts of the subepithelial stroma. After implantation, syndecan-4 was pronounced in pre-decidual and mature decidual cells.
Conclusions: The coordinate balance between the pre- and post-implantation periods suggests a role of these two molecules in the adaptive modification of the uterine microenvironment to receive and implant the embryo.