Biology Today — January 2018

REPRODUCTIVE DUCTS

The reproductive ducts include rete testis, vasa efferentia,
epididymis, vas deferens, urethra and ejaculatory ducts.

Rete Testis

The seminiferous tubules from different areas of a testis
converge to form a network of interconnected tubes, the rete
testis.

Vasa Eerentia

These are fine ciliated ductules that arise from the rete testis.
They vary from 15-20 in number and carry sperms from rete
testis to the epididymis.

Epididymis
It is loosely attached to the outside of testes. It is a long, narrow,
highly coiled tubule which when straightened out measures
approximately 6m. It is differentiated into three parts, i.e., caput
epididymis, corpus epididymis and cauda epididymis.

Function

It is involved in storage, nutrition and physiological maturation of the sperms. It also shows peristaltic contractions to move
the sperms.

Vasa Deferentia

It is a long, narrow, muscular and tubular structure that starts from cauda epididymis, ascends and passes through inguinal
canal, over the urinary bladder in abdomen and finally joins the duct from seminal vesicle to form ejaculatory duct.

Function

It conducts sperms through peristalsis.

Ejaculatory Ducts

These are two short tubes formed by the union of a duct from seminal vesicles and vas deferens. They are composed of fibrous,
muscular and columnar epithelial tissue. Each of these duct pass through prostate gland and joins the urethra.

Function
These ducts carry sperms and secretion of seminal vesicles to urethra.

Urethra

It arises from the urinary bladder and joins the ejaculatory duct to form urinogenital canal. It is differentiated into three parts:

• Prostatic urethra : The first part of urethra surrounded by prostate gland, that arises from urinary bladder and carries
  urine only.


• Membranous urethra : It is the smallest part of urethra and is present behind the lower part of pubic symphysis.


• Penile urethra : The part of urethra that opens at the tip of penis as urethral meatus, (external opening).


• It comprises of two urethral sphincters.

The internal sphincter consists of smooth muscle fibres situated at the neck of the bladder above the prostate gland. The
external sphincter consists of striated muscle fibres surrounding the membranous part of the urethra.

Function
It provides a common passage for semen and urine.

Male v/s Female urethra

The urethra in males is much longer, i.e., approx. 20 cm in length as compared to females (4 cm). Being long it is differentiated

into three regions in males while it remains undifferentiated in females. It carries both urine and semen in males but passes

only urine in females.

Fig.: Front view of male reproductive system

Membranous urethra

Corpus cavernosum

Corpus spongiosum

Spongy urethra

Glans

Penis

Testis

Epididymis

Ductus deferens

Urogenital diaphragm

Bulbourethral gland

Ejaculatory duct

Seminal vesicle

Ampulla

Ureter

Urinary bladder

Prostatic urethra

Prostate gland