Suarez, A. 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.
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Illustration by Brandon Bird. The human body, much like the Internet, is a series of tubes. These tubes transport all sorts of liquids: blood, sweat, tears, jizz, cerebrospinal fluid, and pee-pee. These liquids are supposed to stay flowing. Which is probably why the listenership of the Savage Lovecast lost their collective shit when a man wanted tips on how to keep his semen inside his wife's vagina.
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Fabiana Y. Nakano I. Sandro C. Esteves I. Unexplained infertility diagnosis is made in the presence of a normal semen analysis when tubal patency and normal ovulatory function are established. Among several potential causes, unexplained infertility could be attributed to vaginal pH and cervical mucus abnormalities. Although the vaginal canal and the cervix generally function as effective barriers to sperm, and although the production of mucus is essential to transport them from the vagina to the uterine cavity, these factors receive little attention in the investigation of couples with unexplained infertility. A substantial reduction in sperm number occurs as they transverse the cervix. From an average of to million sperm deposited in the vagina, only a few hundred achieve proximity to the oocyte. Given this expected high spermatozoa loss, a slight modification in cervical mucus may rapidly transform the cervix into a "hostile" environment, which, together with changes in vaginal environment and cervix structure, may prevent natural conception and be a cause of infertility.
What comes to mind when you think of sexual bodily fluids? Does the idea of semen or vaginal discharge turn you on or turn your stomach? We all have different feelings towards the body and its fluids, ranging from lighthearted and positive to deeply shameful and disturbing.