• Humans are sexually reproducing and viviparous.
  • The male reproductive system is composed of a pair of testes, the male sex accessory ducts and the accessory glands and external genitalia.
  • Each testis has about 250 compartments called testicular lobules, and each lobule contains one to three highly coiled seminiferous tubules.
  • Each seminiferous tubule is lined inside by spermatogonia and Sertoli cells.
  • The spermatogonia undergo meiotic divisions leading to sperm formation, while Sertoli cells provide nutrition to the dividing germ cells.
  • The Leydig cells outside the seminiferous tubules, synthesise and secrete testicular hormones called androgens.
  • The male external genitalia is called penis.
  • The female reproductive system consists of a pair of ovaries, a pair of oviducts, a uterus, a vagina, external genitalia, and a pair of mammary glands.
  • The ovaries produce the female gamete (ovum) and some steroid hormones (ovarian hormones). Ovarian follicles in different stages of development are embedded in the stroma.
  • The oviducts, uterus and vagina are female accessory ducts.
  • The uterus has three layers namely perimetrium, myometrium and endometrium.
  • The female external genitalia includes mons pubis, labia majora, labia minora, hymen and clitoris.
  • The mammary glands are one of the female secondary sexual characteristics.
  • Spermatogenesis results in the formation of sperms that are transported by the male sex accessory ducts.
  • A normal human sperm is composed of a head, neck, a middle piece and tail.
  • The process of formation of mature female gametes is called oogenesis.
  • The reproductive cycle of female primates is called menstrual cycle.
  • Menstrual cycle starts only after attaining sexual maturation (puberty).
  • During ovulation only one ovum is released per menstrual cycle.
  • The cyclical changes in the ovary and the uterus during menstrual cycle are induced by changes in the levels of pituitary and ovarian hormones.
  • After coitus, sperms are transported to the junction of the isthmus and ampulla, where the sperm fertilises the ovum leading to formation of a diploid zygote.
  • The presence of X or Y chromosome in the sperm determines the sex of the embryo.
  • The zygote undergoes repeated mitotic division to form a blastocyst, which is implanted in the uterus resulting in pregnancy.
  • After nine months of pregnancy, the fully developed foetus is ready for delivery.
  • The process of childbirth is called parturition which is induced by a complex neuroendocrine mechanism involving cortisol, estrogens and oxytocin.
  • Mammary glands differentiate during pregnancy and secrete milk after child-birth.
  • The new-born baby is fed milk by the mother (lactation) during the initial few months of growth.

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