Background: The Fallopian tube undergoes well-recognized changes during the ovarian cycle. Ciliary beat frequency (CBF) increases during the secretory phase of the cycle. The stimulus is unknown, although CBF is known to be hormone responsive. At ovulation, follicular fluid is released into the peritoneal cavity and enters the Fallopian tube. We hypothesized that this fluid may provide the stimulus for the increase in CBF detected after ovulation.
Methods: Using a technique which records changes in light intensity, we have studied the effect of pre-ovulatory follicular fluid on CBF of Fallopian tube epithelial cells, and compared this with the effect of either peritoneal fluid or culture medium alone. Follicular fluid samples from 13 women undergoing IVF were collected by selective aspiration of individual follicles. Peritoneal fluid was collected from six women undergoing laparoscopic sterilization. Fallopian tubes were collected from 10 women who underwent hysterectomy for benign conditions.
Results: After 24 h incubation, there was a highly significant difference in CBF between the Fallopian tube samples bathed in follicular fluid (mean CBF +/- SEM: 6.34 +/- 0.02 Hz) compared with explants bathed in either medium (4.20 +/- 0.06 Hz) or peritoneal fluid (5.24 +/- 0.03 Hz) (P < 0.005). There was also a significant difference in CBF between tissues bathed in secretory (5.47 +/- 0.03 Hz) compared with proliferative phase peritoneal fluid (4.75 +/- 0.02 Hz) (P < 0.005).
Conclusions: The increase in CBF detected after ovulation may aid ovum pick-up and transport along the Fallopian tube. Factor(s) within human follicular fluid and secretory phase peritoneal fluid may be responsible for this increase in CBF.