- 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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