Human Reproduction

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Reproduction is the process that results in the formation of new individuals of the same kind, usually with slight genetic, structural, and physiological variations. In humans, it is sexual and vivipa…

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Secondary sexual characters are external features that distinguish males and females. In males, they appear at 12-14 years and include beard, moustache, chest hair, broad chest, muscular body, and dee…

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Primary sex organs are the organs that produce gametes and sex hormones. In males, the testes produce sperms and testosterone. In females, the ovaries produce ova, estrogens, and progesterone.

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The testis is the primary male reproductive organ. It is a paired gland in the scrotum, about 4-5 cm long, 2-3 cm wide, and about 25 g in weight. It produces sperms by spermatogenesis and secretes tes…

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The scrotum keeps the testes at a temperature about 2-2.5 degrees C lower than body temperature. This lower temperature is necessary for normal spermatogenesis. If the temperature becomes too high, sp…

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Spermatogonia are diploid germ cells in the seminiferous tubules that develop into sperms. Leydig cells are interstitial cells between seminiferous tubules that produce testosterone. Sertoli cells are…

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One spermatogonium ultimately gives rise to four haploid sperms. This happens through spermatogenesis, including meiosis and spermiogenesis.

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Spermatogenesis has three phases: multiplication phase, growth phase, and maturation phase. In multiplication, spermatogonia multiply by mitosis. In growth, they become primary spermatocytes. In matur…