Tag: reproduction in plants and animals

Seminiferous tubule is the functional unit of testis of man. Each testis has about 250 compartments called testicular lobules, these compartments contain highly coiled tubules called seminiferous tubules. In seminiferous tubules, sperms are produced. Each seminiferous tubule is lined on its inside by two types of cells called male germ cell (spermatogonia) and Sertoli cells. These cells are also called nurse cells as they provide nutrition to the developing sperms. Head of developing sperms are embedded in the sertoli cells. The male germ cells undergo meiotic divisions finally leading to sperm formation.

In mammals, the testes occur in scrotal sacs outside the viscera because of the requirement of low temperature for spermatogenesis. The testes are situated outside the abdominal cavity within a pouch called scrotum. The scrotum helps in maintaining the low temperature of the testes (2–2.5$^o$ C lower than the normal internal body temperature), which is necessary for spermatogenesis. The slightly cooler temperature of the scrotum is necessary for the development of normal sperm. So, the testes start their development in the abdominal cavity and descend into the scrotal sacs during the 7$^{th}$ month of the fetal life, in presence of testosterone hormone.

The region outside the seminiferous tubules in testes is called interstitial spaces. It contain small blood vessels and interstitial cell. These interstitial cells are called Leydig cells. Leydig cells constitute the endocrine tissue of testes. It synthesise and secrete testicular hormones called androgens. Androgens are group of male sex hormones, mainly testosterone.

Sertoli cells occur in human testes. Each lobule of testes contains one to three seminiferous tubules in which the sperms are produced. Each seminiferous tubule is lined on its inside by two types of cells called male germ cells (spermatogonia) and sertoli cells. Sertoli cells are also known as nurse cells. They provide nutrition to spermatozoa. Spermatozoa are developing sperms. Heads of spermatozoa are embedded in the sertoli cells.

The region outside the seminiferous tubules in testes is called interstitial spaces. It contain small blood vessels and interstitial cell. These interstitial cells are called Leydig cells. These cells constitute the endocrine tissue of testes. It synthesise and secrete testicular hormones called androgens. Androgens are group of male sex hormones, mainly testosterone.

The testis is the male reproductive gland in humans and animals. They descend into a scrotal sac which is present beneath the penis. But in whales, elephants, dolphins, rhinoceros testis present internally.

At the age of 4-5 months testis descends into scrotal sacs in rabbits.

Head of the epididymis of the sperm which receives spermatozoa via the efferent ducts of the mediastinum of the testis which is also called as Caput epididymis.

The male sex hormone testosterone is secreted by testes which are under the control of hypothalamus and pituitary gland.

sertoli cells or nurse cells which helps nourishing sperms and spermatogenesis.