Understanding male reproductive system

Hyderabad: This article is in continuation of the previous articles that help you understand what constitutes the biological sciences and its varied branches/ concepts. Today, we let’s discuss the first part of the human reproductive system, with focus on the male reproductive system. The male reproductive system/male genital system consists of a number of sex […]

Hyderabad: This article is in continuation of the previous articles that help you understand what constitutes the biological sciences and its varied branches/ concepts. Today, we let’s discuss the first part of the human reproductive system, with focus on the male reproductive system.

The male reproductive system/male genital system consists of a number of sex organs that are a part of the human reproductive process.
 The sex organs which are located in the pelvic region include a pair of testes (testis) along with accessory ducts, glands and the external genitalia.

Testis

 The testes are situated outside the abdominal cavity within a pouch called scrotum.
 The scrotum helps in maintaining the low temperature of the testes (2.25 degree Celsius lower than the normal internal body temperature) necessary for spermatogenesis.
 Male gonads are homologous with the ovary of female.

 The cavity of the scrotal sac is connected to the abdominal cavity through the inguinal canal.

 Testis is held in position in the scrotum by the gubernaculum, a fibrous card that connects the testis with the bottom of the scrotum.

 A spermatic card formed by the Vas Deferens, nerves, blood vessels and other tissues runs form the abdominal wall, down to each testicle, through the inguinal canal.

 Testis is covered by a dense covering (tunicae) which includes

a. Tunica vaginalis

b. Tunica albuginea
c. Tunica vasculosa

 Each testis is enclosed in a fibrous envelop, the tunica albuginea, which extends inward to form septa that partition the testis in to lobules.
 There are about 250 testicular lobules in each testis.

 Each lobule contains 1 to 3 highly coiled seminiferous tubules.
 A pouch of serous membrane (peritoneal layer) called tunica vaginalis covers the testis.

 Each seminiferous tubule is lined by the germinal epithelium which consists of undifferentiated male germ cells called spermatogonial mother cells and it also bears nourishing cells called sertoli cells.
 Sertoli cells provide nutrition to the spermatozoa and also produce a hormone called inhibin, which inhibits the secretion of FSH.
 The regions outside the seminiferous tubules called interstitial spaces contain interstitial cells of leydig/ leydig cells.

 Leydig cells produce androgens, the most important of which is testosterone.

 Testosterone controls the development of secondary sexual characters and spermatogenesis.
 Other immunologically competent cells are also present.

 The seminiferous tubules open into the vasa efferentia though the reta testis (a network of tubules in the testis, carrying spermatozoa from the seminiferous tubules to the vas efferentia).

Note: The testes descend into the scrotum just before birth. The condition in which the testes do not descend into the scrotum is called Cryptorchidism.

Epididymis:

 The vasa efferentia leave the testis and open into a narrow, tightly coiled tube called epididymis located along the posterior surface of each testis.
 The epididymis provides a storage space for the sperms and gives the sperms time to mature.

 It is differentiated into three regions

a. Caput epididymis

b. Corpus epididymis
c. Cauda epididymis

 The caput epididymis receives spermatozoa via the vasa efferentia of the mediastinum testis (a mass of connective tissue at the bank of the testis that encloses the rete testis).

Vasa Deferentia:

 The Vas Deferens/Ductus Deferens is a long, narrow, muscular tube.
 The mucosa of the Ductus Deferens consists of pseudo stratified columnar epithelium and lamina propria (areolar connective tissue).
 It starts from tail of the epididymis, passes through the inguinal canal into the abdomen and loops over the urinary bladder.
 It receives a duct from the seminal vesicle.
 The Vas Deferens and the duct of the seminal vesicle unite to form a short ejaculatory Duct/Ductus Ejaculatorius.
 The two ejaculatory ducts, carrying spermatozoa and the fluid secreted by the seminal vesicles, converge in the centre of the prostate and open into the urethra, which transport the sperms to outside.

By Dr. Modala Mallesh

Subject Expert

Palem, Nakrekal, Nalgonda
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