HUMAN MALE REPRODUCTION SYSTEM - SCROTUM & TESTES

STD-12      UNIT-6     CHA-3

HUMAN REPRODUCTION

HUMAN MALE  REPRODUCTION SYSTEM - SCROTUM & TESTES

It consists of the following parts : 

• Scrotum . 

• It is a pouch of deeply pigmented skin divided into two separate sacs . 
• Each sac contains one testis . 
• The normal temperature of the testes in the scrotum is about 20–2.5 ° C lower than the internal body temperature . 
• This temperature is the ideal temperature for developing sperms . 
• When the body is chilled , the smooth muscle contracts and brings the testes closer to the pelvic cavity . 
• When the temperature drops movement towards the pelvic cavity allows the testes to absorb heat from the rest of the body so that the sperm cells do not become chilled . 
• The scrotum remains connected with the abdomen or pelvic cavity by the inguinal canals . 
• The spermatic cord , formed from the spermatic artery , vein and nerve bound together with connective tissue passes into the testis through inguinal canal . 

• Testes . 

• Testes are primary sex organs in man . 
• During early foetal life the testes develop in me abdominal cavity but during the 7th month of the development they descendinto the scrotum through inguinal canals . 
• There is a pair of testes that are suspended in the scrotum by the spermatic cords . 
• A fibrous cord that extends from the caudal end of the testis to the scrotal wall is called gubernaculum . 
• 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 peritoneum , called mesorchium supports the testis . section of mammalian 

• ( i ) Protective Coverings ( Tunicae ) . 
• The testis is surrounded by three layers . 
• ( a ) The tunica vaginalis is the outer covering of the tes tis . 
• ( b ) The tunica albuginea is a fibrous cov ering surrounding the testis situated under the tunica vaginalis . 
• ( c ) The tunica vasculosa consists of a net work of capillaries supported by delicate con nective tissue which lines the tunica albuginea. 

• ( ii ) Testicular Lob ules . 
• Each testis has about 250 compartments called testicular lobules . 

• ( iii ) Seminiferous Tubules  .
• Each testicular lobule of testis contains one to three highly coiled seminiferous tubules . 
• Wall of each se miniferous tubule is formed of a single layered germi nal epithelium Majority of cells in this epithelium are cuboidal called male germ cells ( spermatogo nia ) and at certain places , there are present tall sertoli or sustentacular cells . 

• These cells support devel oping germ cells and povide them with nutrition cpecially spermatids . 

• Sertoli cells secrete androgen binding protein ( ABP ) that concentrates testosterone in the seminiferous tubules . 
• Sertoli cells also secrete another protein called inhibin which suppresses FSH synthesis . 
• The cuboidal cells undergo mitosis to produce spermatogonia . Spermatogonia grow into primary spermatocytes which undergo meiosis, producing haploid cells , first secondary spermatocytes and then spermatids . 
• The latter convert into spermatozoa ( sperms ) . 
• Sertoli cells provide nutrition to the developing sperms . 

• ( iv ) Interstitial Cells or Leydig's Cells ( Endocrine portion of the testis ) . 
• In between the seminiferous tubules in the connective tissue , there are present small groups of rounded interstitial or Leydig's cells which secrete androgens ( e.g. , testosterone ) , i.e. , male sex hormones . 

• ( v ) Rete testis and vasa efferentia . 
• The seminiferous tubules are closed at one end but on the other side they join to a network the rete testis from where fine ciliated ductules . the vasa efferentia arise . 
• Thus testes perform two functions , production of sperms and secretion of male sex hormones .

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