DEMONSTRATION OF CYTOKERATIN INTERMEDIATE FILAMENTS IN OOCYTES OF THEDEVELOPING AND ADULT HUMAN OVARY

The intermediate filaments (IF) present in the various cells of human ovaries were studied by immunolocalization using antibodies to cytoker atins (CKs), vimentin, desmin and alpha-smooth muscle (alpha-SM) actin . Oocytes revealed a single paranuclear aggregate, which reacted with antibodies to CKs 8, 18 and 19 both in adult and fetal ovaries. The ex istence of this aggregate was also documented by electron microscopy. Ovarian surface epithelium and granulosa cells consistently coexpresse d CKs 8, 18, 19 and vimentin. During follicle maturation vimentin rema ined unchanged in the granulosa layer while CKs content decreased, sho wing variation in the amount and distribution of the different CK-type s. The-cal cells of secondary and mature follicles showed alpha-SM act in positivity. These contractile fibres increased in mature follicles. Ordinary fibrous stromal cells showed isolated cells which were desmi n and alpha-SM actin positive. A similar pattern of IF expression and distribution existed in all stages of development in fetal and embryon ic ovaries. These results indicate that CKs are present in human oocyt es and that the coexpression of vimentin and CKs can be regarded as a peculiar feature of all ovarian cell types except oocytes and ordinary stromal cells. Contractile properties have been documented associated with a modification in expression of IF proteins. This is likely to r epresent an integral part of folliculogenesis along with the functiona l hormone-dependent changes.