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Animation: Human Spermatogenesis

by Pearson
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>> Spermatogenesis, or sperm formation, in a human male takes place in the testes, which are contained within the sac-like scrotum. Inside of each testis are diploid cells called spermatogonia that are derived from embryonic germ cells. Spermatagonia are stem cells, and divide by mitosis to produce more spermatagonia. In this way, a continuous supply of spermatagonia is always available. During embryonic development, hormones stimulate some of the spermatagonia to form primary spermatocytes. At puberty, increased production of the hormone testosterone stimulates the spermatocytes to begin meiosis. In the first myotic division, meiosis I, a primary spermatocyte generates two secondary spermatocytes. Each haploid secondary spermatocyte then undergoes the second meiotic division, meiosis II. In meiosis II, both secondary spermatocytes generate two haploid spermatids. The result is the production of four haploid spermatids, two from each secondary spermatocyte. These spermatids eventually mature into sperm cells. Thus, during spermatogenesis one diploid spermatocyte gives rise to four haploid sperm cells. The sperm cells produced in the testis are stored in the epididymis. They complete their maturation to functional sperm there.
>> Spermatogenesis, or sperm formation, in a human male takes place in the testes, which are contained within the sac-like scrotum. Inside of each testis are diploid cells called spermatogonia that are derived from embryonic germ cells. Spermatagonia are stem cells, and divide by mitosis to produce more spermatagonia. In this way, a continuous supply of spermatagonia is always available. During embryonic development, hormones stimulate some of the spermatagonia to form primary spermatocytes. At puberty, increased production of the hormone testosterone stimulates the spermatocytes to begin meiosis. In the first myotic division, meiosis I, a primary spermatocyte generates two secondary spermatocytes. Each haploid secondary spermatocyte then undergoes the second meiotic division, meiosis II. In meiosis II, both secondary spermatocytes generate two haploid spermatids. The result is the production of four haploid spermatids, two from each secondary spermatocyte. These spermatids eventually mature into sperm cells. Thus, during spermatogenesis one diploid spermatocyte gives rise to four haploid sperm cells. The sperm cells produced in the testis are stored in the epididymis. They complete their maturation to functional sperm there.