僅數萬隻精蟲可穿越子宮頸到達輸卵管

高達94%精液於同房後30分鐘內自陰道排出，
僅有數萬隻精蟲(< 1%)可穿越子宮頸到達輸卵管，
精蟲可存活於輸卵管中長達2-5天

http://humupd.oxfordjournals.org/content/12/1/23.full


Nevertheless, since pregnancy has been shown to result from intercourse as long as five days before ovulation (Wilcox et al., 1995) human sperm must be stored somewhere in the female tract and the fact that human endosalpingeal epithelium prolongs survival of sperm in vitroindicates that the Fallopian tubes are strong candidates for storage sites.

Sperm transport in the female reproductive tract

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Abstract

At coitus, human sperm are deposited into the anterior vagina, where, to avoid vaginal acid and immune responses, they quickly contact cervical mucus and enter the cervix. Cervical mucus filters out sperm with poor morphology and motility and as such only a minority of ejaculated sperm actually enter the cervix. In the uterus, muscular contractions may enhance passage of sperm through the uterine cavity. A few thousand sperm swim through the uterotubal junctions to reach the Fallopian tubes (uterine tubes, oviducts) where sperm are stored in a reservoir, or at least maintained in a fertile state, by interacting with endosalpingeal (oviductal) epithelium. As the time of ovulation approaches, sperm become capacitated and hyperactivated, which enables them to proceed towards the tubal ampulla. Sperm may be guided to the oocyte by a combination of thermotaxis and chemotaxis. Motility hyperactivation assists sperm in penetrating mucus in the tubes and the cumulus oophorus and zona pellucida of the oocyte, so that they may finally fuse with the oocyte plasma membrane. Knowledge of the biology of sperm transport can inspire improvements in artificial insemination, IVF, the diagnosis of infertility and the development of contraceptives.

Figure 1.

Human female reproductive tract illustrating stages of gamete transport. (A) Sperm entering cervical mucus at external os of cervix. The mucus fills the upper half of the inset. (B) Sperm interacting with endosalpingeal epithelium in Fallopian tube. (C) Hyperactivated motility of sperm in Fallopian tube. (D) Oocyte in cumulus within a transverse section of the tubal ampulla. Artwork by C. Rose Gottlieb.