Changes in mechanical properties of the circular muscle of the isthmus of the human fallopian tube in relation to hormonal domination and postovulatory time.

Using the isthmic circular ring from 76 subjects, the authors investigated the in vitro mechanical response of the fallopian tube to noradrenalin and field stimulation. In the proliferative and menopausal phases, preparations with high plasma levels of estradiol showed a high contractile response. In the secretory phase, responses were inhibitory or low at 4 to 6 and 11 to 14 days after the elevation of basal body temperature and were excitatory at 0 to 3 and 7 to 10 days. The exogenous application of estradiol failed to suppress these inhibitory responses. The findings suggest that the inhibitory response at 4 to 6 days after the elevation of BBT may aid in the release of the ovum from the fallopian tube and that after the ovulation, progesterone is mainly related to the response of the circular muscle to noradrenalin.