semen to coagulate after ejaculation. 60% of the volume of semen is secreted by the seminal vesicles. The prostateis located inferior to the urinary bladder, surrounding the prostatic urethra. It grows in sizes of the years until a man turns 30. The prostate secretes a acidic, milky fluid consisting of: (1) Citric acid (in prostatic fluid to be used by sperm for ATP production via Krebs). (2) Several proteolytic enzymes, including prostate-specific antigen (PSA), pepsinogen, lysozyme, amylase, and hyaluronidase (breaks down the clotting proteins from the seminal vesicles). (3) The function of the acid phosphatase secreted by the prostate is unknown. (4) Seminalplasmin in prostatic fluid is an antibiotic used to destroy bacteria, and decreases the number of naturally occurring bacteria in semen and in the lower female reproductive tract. The fluid from the prostate enter the prostatic urethra through many prostatic ducts. While contributing to sperm motility and viability, prostatic secretion makes up 25% of the volume of semen. The bulbourethral glandsare located inferior to the prostate on either side of the urethra. During sexual arousal, the glands release an alkaline fluid into the urethra, it protects the passing sperm by neutralizing acids from urine in the urethra. To decrease the number of sperm damaged during ejaculation, the glands also secrete mucus that lubricates the end of the penis and the lining of the urethra. Sometimes a drop of thismucus is released upon sexual arousal and erection. There are no sperm cells released from the bulbourethral glands. The semenconsists of sperm and seminal fluid. It is a liquid that contains seminiferous tubules, seminal vesicles, prostate, and bulbourethral glands. The typical volume of semen in an ejaculation is 2.5-5 millilitres, with 50-150 million sperm per mL. For fertilization to occur a large number of sperm is required,only a small fraction of the sperm reaches the secondary oocyte. The prostatic secretion has a higher pH, is milky, and sticky. The seminal fluid functions to provide sperm with a transportation medium, nutrients, andprotection from the acidic environment from within a males urethra and females vagina. The vagina is the receptacle for the penis during sexual intercourse. As an ejaculation occurs, the sperm travels out of the penis and into the vagina. As sperm enter the vagina, the alkaline components of semen from the seminal vesicles, raise the pH of fluid in the vagina, increasing the viability of the sperm. The genetic material from a haploid sperm cell, and a haploid secondary oocyte merge into a single diploid nucleus. About 200 million sperm are ejected into the vagina and only 2 million can reach the cervix of the uterus, and only 200 reach the secondary oocyte. Sperm is only viable for 48 hours after deposition into the vagina. Sperm travels by swimming from the vagina into the cervical canal from the whip like movements of their tails (flagella). From here sperm travels through the rest of the uterus and then into the uterine tube from the contractions of the walls of these organs. The prostaglandins in semen stimulate the uterine
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- Fall '15