Cytologic and histologic observations on the sex hormone dependence of the vulva

The usefulness of vaginal cytology in the assessment of hormonal function is well accepted. Our study established that the epithelial horny cells exfoliated from the vulvar skin also exhibit morphologically visible signs of hormonal activity. Cytologic analysis of 429 vulvar smears from 174 women during 88 cycles and postmortem histologic examination of vulvar specimens from an additional 65 women showed parakeratotic keratinization to be significantly more frequent premenopausally than postmenopausally. A vulvar "parakeratotic index" was developed that fluctuates along with the well-known eosinophilic and karyopyknotic indices of the vagina and corresponds to the plasma estradiol concentrations during the cycle. Administration of estrogens in postmenopausal women initiates a striking increase in the index, which is otherwise quite low during that phase of life.