This section is from the book "Human Sexuality", by J. Richardson Parke. Also available from Amazon: Human Sexuality.
The office of the uterus, along with that of child-bearing, is to receive the semen of the male, and conduct it into the Fallopian tubes, through which, if not interrupted in its journey, it passes onward to the ovaries. But the neck of the womb does not, as many suppose, receive the fluid directly from the intromittent penis of the male. It is thrown, at the orgasm, or "going off" of the latter, into a little pouch-like receptacle at the upper portion of the vagina, formed by the dilatation of the neck of the womb, and is introduced into the latter, frequently, long after intercourse, partly by the amceboid movement of the spermatozoon itself, and partly by a function of the vagina which has been well described by Blundel!,* "This canal," he remarks, "during the heat, is never at rest. It shortens and lengthens, changing continually in its circular dimensions; and when irritated, will sometimes contract to one-third its quiescent diameter." How well adapted this curious movement is, not only for the introduction of the semen at the opening, but to heighten the pleasure of the male, it is needless to explain.
Even if the ejaculatory act of the male were sufficiently vigorous to throw the semen beyond this pouch, or against the mouth of the womb, the cloee approximation of the lips of the latter would effectually bar its entrance. But the cilia, or hair-like processes, of the lining membrane, by their swaying motion, gradually draw it up within the neck—almost as a drop of water pressed between two pieces of glass will rise to the upper margin of the latter—and by a peculiar "swallowing" motion, also possessed by the bladder, attract it inward to the fundus of the womb.
It will thus be seen that fecundation, so far from being simultaneous with the sexual act, may take place at any time subsequently, compatible with the duration of intravaginal cell-life in the spermatoblast; and, also, how futile and foolish are so many of the means resorted to to prevent conception by temporarily covering the neck of the womb with "sponges," " veils," and other mischievous contrivances during the act of copulation.
 
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sexuality, reporduction, genitals, love, female, humans, passion