CHAPTER 2

CHAPTER . The Male Reproductive System . The Female Reproductive System . Gametogenesis . Menstrual Cycle . Fertilisation and Implantation . Pregnancy and Embryonic Development . Parturition and Lactation The testes are situated outside the abdominal cavity within a pouch called scrotum . The scrotum helps in maintaining the low temperature of the testes ( – . o C lower than the normal internal body temperature) necessary for spermatogenesis. In adults, each testis is oval in shape, with a length of about to cm and a width of about to cm. The testis is covered by a dense covering. Each testis has about compartments called testicular lobules (Figure .1b). Each lobule contains 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 (Figure . ). 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 small blood vessels and interstitial cells or Leydig cells (Figure . ). Leydig cells synthesise and secrete testicular hormones called androgens. Other immunologically competent cells are also present. The male sex accessory ducts include rete testis, vasa efferentia , epididymis and vas deferens (Figure .1b). 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. It receives a duct from seminal vesicle and opens into urethra as the ejaculatory duct (Figure .1a). These ducts store and transport the sperms from the testis to the outside through urethra. The urethra originates from the urinary bladder and extends through the penis to its external opening called urethral meatus . Figure . (a) Diagrammatic sectional view of male pelvis showing reproductive system Figure . (b) Diagrammatic view of male reproductive system (part of testis is open to show inner details)