Immunohistochemical analysis of the microanatomy of primate ovary

The ovary is a complex organ composed of cells of diverse lineages. Therefore, in this study we examined whether immunolocalization of various cytoskeletal, epithelial, immune-cell, and neural-associated proteins can differentiate various cells in the baboon and human ovaries. Surface epithelial cells exhibited immunoreactivity for cytokeratin and desmin, however, they did not immunostain for other epithelial markers such as carcinoembryonic antigen or epithelial membrane antigen. Smooth muscle actin was distributed apically whereas vimentin was localized basally in these cells. Ova exhibited strong immunoreactivity for S-100, Leu-M1, and neurofilament and did not show immunoreactivity for epithelial and cytoskeletal proteins. In antral follicles and theca cells, and after formation of corpus luteum, both granulosa and theca cells expressed immunoreactivity for vimentin. Cytokeratins were absent in the preantral and antral follicles. However, atresia and development of apoptosis was associated with expression of immunoreactive cytokeratins in atretic follicles. Development of corpus luteum led to major changes in the immunophenotype of follicular cells. The mere presence of immunoreactivity for cytokeratin and a strong immunoreactivity for desmin in the luteinized granulosa and not in the theca cells allowed discrimination of these cells from each other and from their ancestral cells. Proliferating cell nuclear antigen was present in various ovarian cells except for ovum. The distinct patterns of expression of cytoskeletal, epithelial, and neural-associated proteins in various cells of the ovary facilitates their identification and discrimination.