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Semen |
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semenor seminal fluidWhitish 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 2–5% 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. semen 1. the thick whitish fluid containing spermatozoa that is ejaculated from the male genital tract 2. another name for sperm semen [′sē·mən] (physiology) The fluid that carries the male germ cells. Also known as seminal fluid. Semen a thick, viscid, opalescent, and whitish fluid ejaculated during copulation by human males and males of other animal species. Constituents of semen are spermatozoa and seminal fluid. Semen contains proteins (including enzymes and nucleopro-teins), lipids, carbohydrates, vitamins, prostaglandins, sodium salts, potassium salts, calcium salts, and other organic and inorganic substances. Semen production commences during puberty, reaches its peak at maturity, and diminishes toward old age. The quantity discharged varies from species to species. Men ejaculate 2–6 milliliters (ml), bulls an average of 4–5 ml, stallions 60–100 ml, boars as much as 250 ml, and rams 1–1.5 ml. The potency of semen depends on the quality and quantity of spermatozoa. The quantity of spermatozoa in animal semen varies, totaling approximately 30 percent in rams, approximately 14 percent in bulls, and approximately 7–8 percent in boars and stallions. It may even vary in the same animal, depending on the animal’s conditions of existence. Seasonal secretion of semen is characteristic of most invertebrates and some vertebrates, including fish, amphibians, reptiles, and many birds and mammals. Some diseases are characterized by semen lacking (azoospermia) or deficient in spermatozoa (oligospermia) or by semen with spermatozoa that are motionless (necrospermia) or malformed (teratospermia). Semen analyses are used in forensic medicine and in determining the causes of sterility. In agriculture, an appraisal of the quality of semen is important for the artificial insemination of farm animals, as are the methods used for diluting, storing, and transporting the semen. L. V. DANILOVA Want to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit the webmaster's page for free fun content. |
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