Atresia revisited: two basic patterns of atresia of bovine antral follicles.

Our observations of bovine follicles indicated that the original histological classifications of atresia were inaccurate. A detailed histological, ultrastructural and immunohistochemical study of antral follicles from bovine ovaries collected from an abattoir and from animals whose large follicles had been monitored by ultrasonography was conducted to investigate this further. Nidogen and CD68 were immunolocalized to observe the follicular basal lamina and macrophages, respectively.

Dynamics of the membrana granulosa during expansion of the ovarian follicular antrum.

As an endocrine organ, the ovary has some unique characteristics. The formation, the maturation and the regression of the hormone producing cells really determine the timing, the amount and the type of hormone secreted. Here, we focus on the granulosa cells of ovarian follicles which express 17beta-hydroxysteroid dehydrogenase type 1 and cytochrome P450 aromatase.

Extracellular matrix in ovarian follicles.

A lot is known about the control of the development of ovarian follicles by growth factors and hormones, but less is known about the roles of extracellular matrix in the control of follicular growth and development. In this review we focus on the specialized extracellular matrix of the basal laminas that are present in ovarian follicles. These include the follicular basal lamina itself, the Call-Exner bodies of the membrana granulosa, the subendothelial and arteriole smooth muscle basal laminas in the theca, and the basal lamina-like material of the thecal matrix.

Roles of extracellular matrix in follicular development.

The cellular biology and changes in the extracellular matrix of ovarian follicles during their development are reviewed. During growth of the bovine ovarian follicle the follicular basal lamina doubles 19 times in surface area. It changes in composition, having collagen IV alpha 1-26 and laminin alpha 1, beta 2 and gamma 1 at the primordial stage, and collagen IV alpha 1 and alpha 2, reduced amounts of alpha 3-alpha 5, and a higher content of laminin alpha 1, beta 2 and gamma 1 at the antral stage.

Development of the membrana granulosa of bovine antral follicles: structure, location of mitosis and pyknosis, and immunolocalization of involucrin and vimentin.

The membrana granulosa of the ovarian follicle is termed the 'follicular epithelium', yet there have been no studies considering its epithelial nature and how it changes during follicular development. Therefore, these issues were investigated using histology (n = 45 ovaries), considering its structure and the location of proliferating and dying cells, and drawing analogies with other epithelia. Additionally, differences between the layers of granulosa cells were demonstrated by immunohistochemistry (n = 7 ovaries).