Male Reproductive organs in Human

Male Reproductive System

• The male reproductive system is located in the pelvic region of the body.

• This system consists of a pair of testes , Accessory reproductive  ducts , accessory reproductive glands and  penis as external genitalia.

Testes

• Testes are male gonads and developed in the abdominal cavity.  

• At the last two months before birth, Testes descend through the inguinal canal into a pouch-like structure called scrotum.

• They are located outside the abdominal cavity or located in scrotum because testes require lower temperature than body temperature ( less than 2 to 2.5 degree Celsius) for formation of sperm through spermatogenesis.  

Read more about the Spermatogenesis

Structure of testes -

• Each testis is an oval in shape and covered by the  layer of white fibrous connective tissue called  tunica albuginea. 

• The length of testes is about 4 to 5 cm and width is about 2 to 3 cm.

• Testes are  composed of about 250 compartments called testicular lobules. 

• Each lobule contains  one to three highly couled seminiferous tubules which are functional units of testes. 

• Sperms are produced in seminiferous tubules.  Seminiferous tubules open  into the rete testis. 

• Each seminiferous tubules is lined by sertoli cell and male germ cells. Male germ cell is spermatogonia, responsible for sperm formation.

• Out the seminiferous tubule, there is interstitial spaces. Interstitial cells are present in those spaces.

• Interstitial cells or  Leydig cell, which produce male sex hormones testosterone or Androgen . These cells are located between the seminiferous tubule.

• In addition to this, another type of cells that are located at the periphery of the seminiferous tubule are called sustentacular cells of Sertoli's cells.

• These cells provide nourishment for spermatogenesis.

• Primary germ cells  that are developed during the embryonic development, are responsible for formation of  spermatogonia in the testicular lobule at the layer of seminiferous tubule. Testes also has some immunological competent cell.

• These spermatogonia lead the formation of sperm through spermatogenesis. 

Read more about the female reproductive system

Accessory male reproductive Duct 

• Sperms are  passed through various  ducts to release the outside of the body.

• These various ducts are named accessory reproductive ducts. These are - rete testes, vasa effrentia , Epididymis, vas deferens, ejaculatory duct, and urethra.

Epididymis

• Sperms are released from seminigerous tubules of testes through rete testes and  enter  into the vas effrentia.

• Vas effrentia lead into epididymis and transport sperm for maturation.

• Each epididymis is a long and coiled  tube When the sperm  make entry into epididymis they are immature and not able to fertilize the ova.  

• The function of epididymis is   maturation and storage of sperm. Mature sperm are stored in the lower portion of the epididymis.

• Epididymis open into vas deferens.

Vas Deferens or Ductus Deferens

• The  vas deferens is a muscular tube that runs from  the epididymis.

• It begins from the  epididymis and  turns over  the posterior margin of the testes In form of a ring .

• The vas  deferens make entry  through the inguinal canal and pass along the pelvic wall. 

• It crosses the ureter and posterior portion of the urinary bladder, and then descends toward the prostate gland.

• Each Vas deferens enlarges to form an ampulla. Sperms are  also stored in vas deferens, near the epididymis.

• The  peristaltic movements push  the sperm through the tube to move outside from gas deferens.

• The vas deferens is also a component of the spermatic cord. These spermatic cords which have vascular and neural structures provide the supply of blood the testes.

• The spermatic cord contains the vas deferens, testicular artery and veins, lymph vessels, testicular nerve, cremaster muscle.

• The cremaster muscles  elevates the testes  at the times of sexual stimulation.

• Vas deferens is extended in abdomen and make loop over the urinary bladder.
• Vas deferens receive a duct from seminal vesicle and open outside as ejqculatory duct into Urethra.

Ejaculatory Duct

• Ampulla part of each vas deferens joins the  seminal vesicle  to form an ejaculatory duct.

• Each ejaculatory duct passes through the prostate gland and open into the urethra.

Urethra

• The urethra extends from the urinary bladder and opens externally  at the tip of the penis through urethral meatus.

• It is a common passage through which sperm and urine  release from the urinary system. 

• The male urethra is divided into three regions - Prostatic urethra, Membranous urethra and penile urethra. The ducts of bulbourethral glands open into the penile urethra.

Accessory male reproductive  Glands

• The accessory glands of the male reproductive system are the seminal vesicles, prostate gland, and the bulbourethal gland.

• These glands secrete fluids and make semen along with the sperm. Secretion of these glands is called seminal plasma that is rich in fructose, calcium and some enzymes.

Seminal Vesicles

• The Seminal vesicles are paired and join with the vas deferens  to form an ejaculatory duct that  opens into the urethra. 

• The fluid from the seminal vesicles is rich in  fructose, which provides an energy source for the mobility and viability of the sperm. 

Prostate gland

• The prostate gland is single and  located just inferior to the urinary bladder and encircles the urethra. 

• It is also called walnut gland. The secretions of the prostate are  milky  and alkaline. The secretion of prostate glands is  to provide  the motility of the sperm.

Bulbourethral Glands

• The  bulbourethral gland or Cowper's glands are paired and located near the base of the penis.

• During the  sexual stimulation, the bulbourethral glands secrete an alkaline fluid. 

• This fluid neutralizes the acidity of the urine and provides lubrication for  the penis during intercourse.

Penis

• The penis is a copulatory organ, located near the scrotum. Penis is also called as male external genitalia. 

• Penis plays a role for insemination or it transfers sperm to the vagina. The penis consists of three columns of tissue.

• Out of these, The two dorsal columns are the corpora cavernosa And the single is  ventral column is corpus spongiosum.

• Penis is made up of special tissue that help in erection of penis for the insemination.

• The enlarged end of penis is glans penis which is covered by skin called fore skin.

Seminal Fluid or Semen

• Seminal fluid or semen is  alkaline in nature and is   mixture of sperm and secretions from the accessory glands.

• Secretions from the seminal vesicles make about more than half  of the volume of the semen and remain is from the prostate gland. 

• The secretions from the bulbourethral gland contribute only a small volume of semen.