Male and female reproductive system of leaches- Essay

Leaches are hermaphrodite i.e., possess both male and female reproductive organs in the same individual, but cross fertilization is a rule.

Male reproductive organs:

These are as follows:

1. Testis sac:

From segment 12 to 22 each segment possesses one pair of testis sac, located one on either side of ventral nerve cord. It is really a constricted off portion of coelom. Spermatozoa formed by sperm mother cells which bud off from the wall of testis sac.

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2. Vasa efferentia:

From the testis sac spermatozoa pass on to the vasa-efferentia which is a short duct. It runs outwards to join the vas deferens of its own side.

3. Vasa deferentia:

Each vasa deferens is a slender, longitudinal wavy duct lying on ventral body wall parallel to the ventral nerve cord from 11^th to 22^nd segment.

4. Epididymis:

In 10^th segment vas deferens swells up and forms a convoluted mass, the epididymis or sperm vesicle. Each epididymis serves to store the sperms, come from vas deferens.

5. Ejaculatory ducts:

From the anterior inner end of each epididymis arises a short, narrow ejaculatory duct or ductus ejaculatoris.

6. Atrium:

Ejaculatory duct of both sides join a median pyriform sac, the atrium extending from the 9^th and 10^th segments and opens it outside by the male genital pore.

Its broad anterior neck-like part forms penis sac, containing tubular muscular penis. Prostate glands secretion mixes well with sperms ejaculated in prostate chamber forms bundles or packets of sperms, the spermatophores.

These spermatophores then transfer into the vagina of other leach through penis during copulation.

Female reproductive organs:

These are very compact and following:

(i) Ovisacs:

Ovisacs are the coelomic sacs situated ventrally in 11^th segment one on either side of ventral nerve cord.

(ii) Ovaries:

Ovary is a delicate tubular ova producing organ, found enclosed in each of the ovisacs.

(i) Oviduct:

At the base of each ovisac the ovary is continued into a short and slender tube, the oviduct which runs inwards and backwards.

(ii) Common Oviduct:

Two oviducts of both sides unite in the 11^th segment to form common oviduct. The place of their union is covered by a thick layer of albumen glands which open into the common oviduct.

Posterior part of common oviduct which is free from albumen gland is folded and leads into the vagina.

(iii) Vagina:

It is muscular pear shaped body found in 11^th segment. It increases in size and also becomes internally folded during breeding season. Anteriorly it opens outside by female genital pore.

Ova are budded off from ovaries into their ovisacs. From here they pass down from the oviducts to the common oviduct.

Here they mixes with albumen and then are passed into vagina, where they are stored till fertilization.