Changes during the menstrual cycle in cytosolic and nuclear concentrations of progestagen receptor in the human Fallopian tube.

[3H]R5020 was bound to cytosolic and nuclear samples of human Fallopian tube with high affinity and specificity. The cytoplasmic and nuclear concentrations of progestagen receptor varied, throughout the menstrual cycle, in the ampulla, isthmus and fimbria. Concentrations were higher at the late proliferative stage of the cycle than at the early proliferative and late secretory stages. A positive linear regression was observed between cytosolic and nuclear progestagen receptor concentrations and plasma oestradiol levels. A negative linear relationship was observed between cytosolic progestagen receptor concentration and plasma progesterone levels during the secretory stages of the menstrual cycle.