Cell proliferation patterns in the equine endometrium throughout the non-pregnant reproductive cycle.

The research focuses on understanding the cell proliferation patterns in the endometrium of mares during their non-pregnant reproductive cycle, using the Ki-67 antigen as a proliferation marker and employing the MIB1 antibody specifically for equine tissues. The article discusses how these cell division rates vary under the influence of fluctuating estrogen levels, a process which seems to significantly affect the cell types in the superficial strata. It also addresses potential implications for mares with reproductive issues.

Methodology

• The study employed immunohistochemical detection of the Ki-67 antigen to track the cell division activity within the mare’s endometrium.
• The monoclonal MIB1 antibody was used, which was validated specifically for its application on equine tissues. The verification was achieved by observing its interaction with activated peripheral blood lymphocytes.
• The research observed endometrial biopsies from 26 non-pregnant mares at different stages during their reproductive cycle.
• The counting of the proportion of positively stained nuclei in five random areas on each histological section helped to determine the percentage and type of cell that was proliferating at each stage.

Findings

• Cell division rates in the superficial strata — which includes the luminal epithelium, the epithelium of the gland necks, and the stromal cells of the stratum compactum — peaked during estrus, likely due to the influence of estrogens secreted by the growing ovarian follicles.
• The cell division in the deeper secretory portions of the endometrial glands was limited to a brief period between day 3 and day 7 of diestrus, suggested as a delayed response to dropping estrogen levels post-ovulation.
• Some glands in sub-fertile mares did not follow the expected pattern of increased epithelial division at this stage.
• After day 7 of diestrus, cell division rates in the endometrium dropped to basal levels, remaining low for as long as progesterone levels were elevated, even during prolonged diestrus.

Implications

• The findings facilitate a better characterization of cell division patterns in the endometrium of mares.
• This method can prove instrumental in understanding endometrial responses in both fertile and sub-fertile mares, aiding in future reproduction health monitoring.