Human Reproductive System - The Male Reproductive System

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Topics

  • The male reproductive system
  1. Testes
  2. Accessory ducts
  3. Accessory glands
  4. External genitalia
  • Histology of seminiferous tubules

Notes

The male reproductive system:

  • The male reproductive system is located in the pelvis region.

    Diagrammatic sectional view of a male pelvis showing reproductive system

  • Male reproductive system includes:
  • A pair of testes (primary sex-organ)
  • Accessory ducts (rete testis, vas a efferentia epididymis, vas deferens)
  • Accessory glands (paired seminal vescile, a prostate, and paired bulbourethral gland)
  • External genitalia (Penis)

    Diagrammatic view of male reproductive system

Notes

A) Testes:

  • The testes are situated outside the abdominal cavity within a pouch called scrotum.
  • The scrotum helps in maintaining the low temperature of the testes (2-2.5oC lower than the normal internal body temperature) necessary for spermatogenesis.
  • In adults, each testis is oval in shape, with a length of about 4 to 5 cm and a width of about 2 to 3 cm.
  • The testis is covered by a dense covering.
  • Each testis has about 250 compartments called testicular lobules.

Histology of Seminiferous tubules:

  • Each lob contain one to three highly coiled seminiferous tubules in which sperms are produced.
  • Each seminiferous tubule is lined on its inside by two types of cells called male germ cells (spermatogonia) and Sertoli cells.
  • The male germ cells undergo meiotic divisions finally leading to sperm formation, while Sertoli cells provide nutrition to the germ cells.
  • The regions outside the seminiferous tubules called interstitial spaces contain:
    1) Small blood vessels
    2) Interstitial cells or Leydig cells
    3) Other immunologically competent cells
  • Leydig cells synthesise and secrete testicular hormones called androgens, also called male sex hormones.

    Diagrammatic sectional view of seminiferous tubule

B) Accessory ducts:

  • The male sex accessory ducts include rete testis, vasa efferentia, epididymis, and vas deferens.
  • The seminiferous tubules of the testis open into the vasa efferentia through rete testis.
  • The vasa efferentia leave the testis and open into epididymis located along the posterior surface of each testis.
  • The epididymis leads to vas deferens that ascends to the abdomen and loops over the urinary bladder.
  • Vas deferens receives a duct from seminal vesicle and opens into the urethra as the ejaculatory duct, that stores and transports sperm from the testis to outside via urethra.
  • The urethra originates from the urinary bladder and extends through the penis to its external opening called urethral meatus.

C) Accessory glands:

  • The male accessory glands include paired seminal vesicles, prostate, and paired bulbourethral glands.
  • Secretion of all these glands are constitutively called seminal plasma which is rich in fructose, calcium, and certain enzymes.
  • The secretions of bulbourethral glands also helps in the lubrication of the penis.

D) External genitalia:

  • The penis is the male external genitalia.
  • Penis is made up of special tissue that helps in erection of the penis to facilitate insemination.
  • The enlarged end of penis called the glans penis is covered by a loose fold of skin called foreskin or prepuce.
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