sperm(redirected from sperm live-dead ratio)
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spermatozoon(spûr'mətəzō`ən, –zō`ŏn), in biology, the male gamete (sex cell), corresponding to the female ovumovum
, in biology, specialized plant or animal sex cell, also called the egg, or egg cell. It is the female sex cell, or female gamete; the male gamete is the sperm. The study of the ovum is included in the science of embryology.
..... Click the link for more information. 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 chromosomechromosome
, structural carrier of hereditary characteristics, found in the nucleus of every cell and so named for its readiness to absorb dyes. The term chromosome
..... Click the link for more information. ) of the male parent, and a slender whiplike process (flagellum), which provides the motility necessary for fertilizationfertilization,
in biology, process in the reproduction of both plants and animals, involving the union of two unlike sex cells (gametes), the sperm and the ovum, followed by the joining of their nuclei.
..... Click the link for more information. in a fluid medium. In higher plants the sperm is contained in the pollenpollen,
minute grains, usually yellow in color but occasionally white, brown, red, or purple, borne in the anther sac at the tip of the slender filament of the stamen of a flowering plant or in the male cone of a conifer.
..... Click the link for more information. 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.
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.