No abstract

The aim of this study was to analyze through histomorphometry, epithelial structures of the mare's endometrium classified according to Kenney and Doig (1986). Histomorphometric analysis of the luminal and glandular epithelial cell heights, glandular lumen diameter, glandular density, percentage of glands with apparent lumen and with intraluminal secretion, and a descriptive analysis of the endometrium was made in 65 endometrial biopsies. Samples were collected during estrus (n=30) and diestrus (n=35), fixed in Bouin's solution, embedded in paraffin HxE and classified according to Kenney and Doig (1986) categories. Groups of IIa category obtained the greatest medium cell heights for luminal and glandular epithelium, and groups of III category obtained the smallest values, during estrus and diestrus. The medium heights of luminal epithelium, glandular epithelium and glandular lumen diameter of samples collected during estrus were greater than those collected during diestrus. The gland density was greater during diestrus than estrus. This work showed that histomorphometry could improve the consistency in biopsy evaluation by furnishing objective data.

Immunohistochemical expression of proliferating cell nuclear antigen (PCNA) was evaluated in the endometrium of mares during estrus and at early diestrus. Three samples were collected by endometrial biopsy from 10 mares, on estrus/ second day, in the ovulation day and seven days after the ovulation day. PCNA expression was high in luminal epithelium and low in endometrial glands on samples taken on estrus/second day and on the ovulation day (p < 0.05). For samples collected on the seventh day following ovulation, the averaged PCNA immunostaining was higher in glandular epithelium (p < 0.05). The study revealed that luminal epithelial cells exhibit higher proliferation during estrus and glandular epithelial cells exhibited higher proliferation during diestrus.Keywords: Cell proliferation. Endometrium. Immunohistochemical. Mare. PCNA. ResumoA expressão do antígeno núcleo celular proliferante (ANCP) foi avaliada no endométrio de éguas durante o estro e início do diestro. Em cada uma de dez éguas foram efetuadas biópsias do endométrio em três momentos dos respectivos ciclos reprodutivos: segundo dia do estro, dia da ovulação e sete dias após a ovulação. Nas amostras colhidas no segundo dia do estro e no dia da ovulação, a expressão do ANCP foi elevada no epitélio luminal e baixa nas glândulas endometriais (p < 0,05). Nas amostras colhidas no sétimo dia após a ovulação, a média de ANCP imunologicamente corado foi maior no epitélio glandular (p < 0,05). O estudo revelou que as células do epitélio luminal apresentaram a maior proliferação durante o estro e que as células epiteliais glandulares apresentaram a maior proliferação durante o diestro.Palavras-chave: Proliferação celular. Endométrio. Imuno-histoquímica. Égua. ANCP.