In male earthworm in which segment seminal vesicle is present
Answers
A] Male reproductive organs
They consist of following parts:
Testes
There are two pairs of small, white and lobed testes, located in 10th and 11th segment.
They lie ventro-laterally below the alimentary canal, close to mid-ventral line on either side of ventral nerve cord.
Each testis consists of 4-8 finger like projections/ processes, containing round cells called spermatogonia.
They are enclose within the testis sac.
Function: They produce sperm.
Testis sac
Testes are enclosed by wide, thin-walled, whitish structure known as testis sac.
There are two testis sac present in 10th and 11th segment.
Testis sac communicates with a pair of seminal vesicles of succeeding segments.
The testis sac of 11th segment become larger as they enclosed the seminal vesicles of that segment.
They develop from the body cavity as small out-growth and lateral become saccular.
Seminal vesicles
They are large, white, spherical structure found in two pairs, located in 11th and 12th segments.
They are also called septal pouches as they are formed as outgrowth of septa.
Seminal vesicles of 11th segment are smaller and are surrounded by testis sac of the same segment and communicates with the testis sac of 10th segment while those of 12th segment are free and communicate with the testis sac of 11th segment.
Function
Spermatogonia undergo maturation division to form spermatozoa or sperm.
Maturation of sperm takes place in seminal vesicles.
Spermiducal funnel/ spermatic funnel
They are cup like curvature found in two pairs.
They are ciliated sperm funnels, lying below each testis in the segment 10th and 11th segment and enclosed within the same testis sac.
Function
Mature sperms from seminal vesicles move back to the testes sac and pass through the spermiducal funnel into vasa differentia.
Vasa deferentia
They are elongated narrow ciliated thread like tubular structure which extends from 12th to 18th segment.
They are found in two pairs and each pair lie on either side of alimentary canal.
They extends from 12th to 18th segment.
In 18th segment they join together with a thick prostatic duct and forms common prostatic and spermatic duct.
Function
They collect sperm from spermatic funnel and give to prostate gland.
Prostate gland (A gland in male that surrounds and opens into the urethra where it leaves the bladder)
There are a pair of large, white, flat, solid, irregular and lobulated gland, extending from 16th to 20th or 17th to 21st segment.
Each gland consists of large glandular part-containing many lobules and small non-glandular part-consisting of several small ductules.
From each prostate gland emerges a short, thick curved prostatic duct in 18th segment.
The prostatic duct joins the two vasa deferentia of its own side unite to form a common prostatic and spermatic duct.
Prostatic duct opens separately through a male genital aperture on the ventral side of 18th segment.
Thus each genital aperture has 3 separate apertures- two of the vasa deferentia and one of the prostatic gland.
Function
It produce prostatic fluid which is alkaline in nature. It activates sperms. And also it keeps sperm motile.
Accessory glands
These are two pair of whitish, spherical structures found one pair in each of the 17th and 19th segment.
Found on the ventro-lateral body wall on either side of the ventral nerve cord.
They open to the exterior by a number of ducts on two pair of genital papillae, situated in 17th and 19th segment.
Secretion of these gland helps in holding two worms during copulation.
Function
They help in pseudocopulation.
Male genital pore
It is found in one pair located in 18th segment.
Function
It acts as male genital pore.
Explanation: