Stage-specific and differential expression of gap junctions in the mouse ovary: connexin-specific roles in follicular regulation

Gap junction communication plays an essential role in follicle growth. Immunocytochemistry and confocal microscopy were used to examine the expression of gap junction connexins of the α and β subfamilies in follicles from primordial to preovulatory stages in the ovaries of prepubertal and adult mice. Connexin-specific antibodies detected α1, α4, α6, β1, β2 and β4 connexins within follicles. In adult ovaries connexin immunolabelling was stronger in larger (more mature) follicles than it was in smaller follicles, with comparatively reduced labelling detected in prepubertal ovaries. In healthy follicles, labelling for α subfamily connexins was detected between granulosa cells, whereas labelling for β subfamily connexins was found in the theca. Labelling for β subfamily connexins and α4 connexin (preantral stage) was detected on the oocyte surface membrane. In atretic follicles, labelling for β4connexin appeared between the granulosa cells. These results demonstrate that αand β connexin subfamilies are segregated to separate cellular compartments in the mouse follicle. The results are discussed in the light of possible roles for differential gap junctional communication in the regulation of folliculogenesis, oocyte maturation and atresia.