Tag: the reproductive system

• The testis is the male gonad in animals. The primary function of the testes is to produce sperm (spermatogenesis) and to produce androgens, primarily testosterone.

• 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. It is formed during the last stage of spermatogenesis. This stage is known as spermiogenesis.
•  In this step, spermatids are transformed into spermatozoa (sperms) by the process of metamorphosis. Heads of spermatozoa are embedded in the Sertoli cells.

The primary sex organ in the male is testis. Besides producing sperms they also produce hormones. Penis and prostate are examples of secondary sex organs. The scrotum is not a sex organ.

The tubular structures present inside the testis are known as seminiferous tubules. These tubules are responsible for producing the sperm cells through a process called spermatogenesis. 

Human male germ cell is sperm. Each sperm is a single cell. During the last step of spermatogenesis, spermatids are transformed into spermatozoa by the process of metamorphosis. These spermatozoa are known as sperms. Mature sperm consists of a head, a neck, a middle piece and a tail. A plasma membrane envelops the whole body of sperm. The sperm head contains a very little cytoplasm, an elongated haploid nucleus, the anterior portion of which is covered by a cap-like structure, acrosome. Sperm fertilizes with ovum and leads to the formation of zygote.

The sperms are produced in the testes in which the process of spermatogenesis takes place. The sperms move to the epididymis where they mature and are stored. The sperms pass through the vas deferens and then through the urethra. The sperms are ejaculated through the penis which is the copulatory organ. 

The testes are situated outside the abdominal cavity within a pouch called scrotum. The temperature in scrotum necessary for sperm formation should be 2$^o$C below body temperature. The slightly cooler temperature of the scrotum is necessary for the development of normal sperm. The testes of human males are extra-abodominal because it descends into the scrotal sacs.