Sperm (redirected from Sperma)

sperm or spermatozoon (spûr'mətəzō`ən, –zō`ŏn), in biology, the male gamete (sex cell), corresponding to the female ovum in organisms that reproduce sexually. In higher animals the sperm is produced in the testis of the male; it is much smaller than the ovum and consists primarily of a head, whose nucleus bears the hereditary material (see chromosome) of the male parent, and a slender whiplike process (flagellum), which provides the motility necessary for fertilization in a fluid medium. In higher plants the sperm is contained in the pollen grain and is conveyed to the ovum by the pollen tube; in some lower plants (e.g., mosses and ferns) the sperm is actively motile.

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sperm

 or spermatozoon

Male reproductive cell. In mammals, sperm are produced in the testes and travel through the reproductive system. At fertilization, one sperm of the roughly 300 million in an average ejaculation (see semen) fertilizes an egg (see ovary) to produce an offspring. At puberty, immature cells (spermatogonia) begin a maturation process (spermatogenesis). A mature human sperm has a flat, almond-shaped head, with a cap (acrosome) containing chemicals that help it penetrate an ovum. It is essentially a cell nucleus, with 23 chromosomes (including either the X or Y that determines the child's sex). A flagellum propels the sperm, which may live in a woman's reproductive tract for two to three days after sexual intercourse, to the egg. Sperm may be frozen and stored for artificial insemination.

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sperm

1. another name for semen

2. a male reproductive cell; male gamete

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sperm [spərm]

(histology)

spermatozoon

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Sperm 

in plants, a nonmotile male sexual cell, or gamete. In higher plants, sperms are nonmotile because they develop inside a pollen tube, which forms upon the germination of a pollen grain (microspore). Fertilization takes place after the pollen tube ruptures upon reaching the female sex organ—the archegonium in gymnosperms or the embryo sac in angiosperms. In gymnosperms a pair of sperms forms as a result of the division of the generative cell. One of the sperms participates in fertilization, and the other dies. Both sperms participate in the fertilization of angiosperms, one fertilizing the ovum, and the other the secondary nucleus of the embryo sac. The male gametes of pteridophytes, bryophytes, and some gymnosperms (including Cycadopsida and ginkgos) are called spermatozoids; they are flagellate and motile.