CYTOKERATIN EXPRESSION IN THE DEVELOPING VAGINA OF THE POSTNATAL GERBIL (MERIONES-UNGUICULATUS)

During postnatal development the vaginal epithelium of the Mongolian g erbil is transformed from two to three layers into a stratified, first mucified subsequently keratinized squamous epithelium. Changes in the expression of cytokeratins were studied and the immunohistochemical r esults compared with the ultrastructural findings at the corresponding stage. The first 10 postnatal days (days pn) were characterized by a moderate, positive immunoreaction for pancytokeratin in all vaginal ce ll layers. A faint reaction was caused by mAB CK 18.01 against CK 1, 5 , 6 and 8. The appearance of mucous granules in the luminal cells afte r 15 pn seemed to coincide with an increase in cytokeratins. The immun oresponse for pancytokeratin in these cells was very intense compared with the reaction in the basal cell layers. Mucocytes during developme nt and at proestrus were the only cells which reacted faintly positive with mAB against CK 18 alone. The keratinizing epithelium, which diff erentiates after day 40 pn, reacted strongly positive for pancytokerat in in the keratinizing layers, desquamating, fully keratinized cells, however, showed a negative reaction. The data indicate that mucocytes are not transformed squamous keratinized cells, but represent a cell c ategory with its individual differentiation potential. Vimentin was no t expressed. Neither the epithelium of the sinus vagina nor of the Mul lerian vagina displayed any response.