The dynamics of rapid sperm transport through the female genital tract: evidence from vaginal sonography of uterine peristalsis and hysterosalpingoscintigraphy

Vaginal ultrasonography of uterine peristalsis during the follicularphase of the menstrual cycle demonstrates an increasing frequencyand intensity of subendometrial and myometrial peristaltic wavesas the follicular phase progresses. During this time the numbersof contraction waves with a fundo-cervical direction decreaseconsiderably in favour of waves of contraction with a cervico-fundaldirection. There is evidence that rapid sperm transport throughthe female genital tract is passive and is provided by theseuterine contractions. Using hysterosalpingoscinti-graphy, rapidsperm transport was studied by placing technetium-labelled albuminmacrospheres of sperm size at the external os of the uterinecervix and following their path through the female genital tractAscension of the macrospheres occurred immediately followingdeposition at the external os of the cervix. As early as 1 minthereafter, the macrospheres had reached the intramural andisthmical part of the tube. Quantitatively, the extent of ascensionincreased with progression of the follicular phase. While onlya few macrospheres entered the uterine cavity and even fewerthe tubes during the early follicular phase, the proportionof macrospheres that entered the uterine cavity increased dramaticallyduring the mid-follicular phase despite continuing limited entryinto the tube. During the late follicular phase there was considerableascension of the macrospheres which was directed preferentiallyinto the tube ipsilateral to the dominant follicle. These dataindicate that rapid transport of the spermatozoa through thefemale genital tract is under the endocrine control of the dominantfollicle, ensuring the preferential accumulation of spermatozoaat the site of fertilization.