Localisation of E-cadherin, perlecan, nidogen 2 and collagen type I in small healthy and atretic follicles. (A, B) E-cadherin (red) is restricted to the membrana granulosa and is strongly expressed in atretic follicles. Perlecan (green) marks the follicular and sub-endothelial basal lamina and is expressed in the cytoplasm of granulosa cells of healthy and atretic follicles. (C, D) Nidogen-2 (red) is localised to the basal lamina of both follicle types, but is only expressed in the granulosa layer of small atretic follicles. Collagen type I (green) is not localised to the granulosa cells. It is restricted to the thecal and medullar stroma. The star indicates the granulosa layer. Bar = 50 μm.