Whitish viscous fluid emitted from the male reproductive tract that contains sperm and liquids (seminal plasma) that help keep them viable. Sperm cells, produced by the testes in humans, represent 2–5percnt of semen volume; fluids from tubules, glands, and storage areas of the reproductive system bathe them as they travel down, nourishing them, keeping them motile, or participating in certain chemical reactions. During ejaculation, liquids from the prostate gland and seminal vesicles dilute the sperm and provide a suitable, slightly alkaline environment. An average ejaculation of a human male expels 0.1–0.3 cu inches (2–5 ml), containing 200–300 million sperm.
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The thick secretions contain proteins, enzymes, fructose, mucus, vitamin C, flavins, phosphorylcholine and prostaglandins. The high fructose concentrations provide nutrient energy for the spermatozoa when stored in semen in the laboratory. Spermatozoa ejaculated in the vagina are not likely to have contact with the seminal vesicular fluid but transfer directly from the prostatic fluid into the cervical mucus as the first step on their travel through the female reproductive system. The fluid is expelled under sympathetic contraction of the muscularis muscle coat.
The height of these columnar cells, and therefore activity, is dependent upon testosterone levels in the blood.
The lumen is large and stores the fluid secretions (but not spermatozoa) between ejaculations.
From inside to out, the layers are: