Morphology of the Oviducts and Endometria of Cynomolgus Macaques during the Menstrual Cycle 1

Abstract

The reproductive tracts of 27 cynomolgus macaques were sampled during the menstrual cycle and the cytologic changes in the oviductal epithelium correlated with changes in the serum levels of estradiol (E2) and progesterone (P) and with the histology of the ovaries and the endometria. An orderly sequence of changes in the oviductal epithelium from the early follicular to the late luteal phase was identified and classified into 8 stages, named as follows: preciliogenic, ciliogenic, ciliogenic-ciliated, ciliated-secretory, early regression, late regression and full regression. The preciliogenic and ciliogenic phases were coincident with menses and the early follicular phase. The ciliogenic-ciliated, ciliated-ciliogenic and ciliated-secretory phases during which the oviductal epithelium became progressively more differentiated were coincident, respectively, with the midfollicular, late follicular and periovulatory phases of the cycle. The early, late and full regression stages during which the epithelium became progressively more atrophied, deciliated and nonsecretory were coincident, respectively, with the early, mid- and late luteal phases of the cycle. The cyclic changes in the endometrium of cynomolgus macaques were similar to those reported for the rhesus macaque.