CYCLICAL CHANGES IN THE VAGINAL SMEARS OF SENILE NULLIPAROUS AND MULTIPAROUS RATS

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Abstract
SUMMARY: The pattern of the vaginal smear of senile nulliparous rats can be subdivided into three categories: (1) prolonged cycles characterized by long phases of vaginal cornification; (2) prolonged cycles associated with long dioestrous periods and occasional mucification; and (3) sporadic mucification and appearance of epithelial cells which follow so irregular a course that no cycles can be detected. The first type of pattern is associated with absence of corpora lutea, and a high incidence of pituitary enlargement and mammary fibroadenomata. The second and third types are associated with the presence of excessively large corpora lutea, and a lower incidence of pituitary enlargement and fibroadenomata. In contrast, the majority of senile multiparae show normal or only slightly atypical oestrous cycles. The incidence of excessively large corpora lutea, pituitary enlargement and mammary fibroadenomata is markedly lower than in the nulliparae.