Binding of estrogen and progestin in the human fallopian tube

The estrogen and progestin receptor concentrations in the human fallopian tube have been investigated. The binding of estrogen and progestin to their cytoplasmic and nuclear receptor proteins were of high affinity and specificity. The cytoplasmic and nuclear receptor concentrations in the isthmus, ampulla, and fimbria did not differ significantly. The nuclear progestin receptor concentrations in the isthmus and fimbriae were significantly higher (P less than 0.05) in the follicular phase than in the luteal phase of the menstrual cycle. In the postmenopausal tubes the receptor concentrations was low, whereas the progestin receptor concentration was quite high.