Reproductive system of frogs

Reproductive system of frogs

The male frog and the female frog can be distinguished even by their external morphological characters. The organs concerned with the production of gametes [sperms and ova (egg)] are called principal reproductive organs. The organs concerned with the transport of gametes further from the gonads are called accessory reproductive organs.

REPRODUCTIVE ORGANS OF MALE FROG

In the male frog the principal reproductive organs are a pair of testes and the accessory reproductive

organs are :

1. Vasa Efferentia,

2. Bidder's Canal,

3. Collecting Tubules,

4. Urinogenital Ducts,

5. Cloaca and

6. Cloacal Aperture.

 

1. Male reproductive organs consists of a pair of yellowish ovoid testes, which are found adhered to the upper part of kidneys by a double fold of peritoneum called mesorchium. Vasa efferentia are 10-12 in number and after arising from testes run through the mesorchium and enter the kidneys of their side. In kidneys, these open into Bidder's canal, which finally communicates with the urinogenital duct.
   
   This duct emerges from the kidneys and finally opens into the cloaca. The cloaca is a small, median chamber that is used to pass faecal matter, urine and sperms to the exterior. 

 
REPRODUCTIVE ORGANS OF FEMALE FROG

 

In the female frog the principal reproductive organs are a pair of ovaries and the accessory reproductive organs are :

1. A pair of Oviducts,

2. Cloaca and

3. Cloacal Aperture.

Ovary : In the young frog each ovary is small, flat and lobulated. In adult frog this is the same case during the period of year other than breeding season. The ovary is enveloped by mesovarium, a thin layer of peritoneum. Several hollow sac-like structures form the ovary. The lobulated appearance of the ovary due to those structures. Initially the colour of the ovary is yellowish with small black spots. The lumen of the ovary is part of the coelom. It is filled with coelomic fluid. During the breeding season the wall of the ovary becomes studded with a large number of ovarian follicles. Each Ovarian Follicle contains a developing Egg. The ovarian follicles project towards the lumen of ovary. Such an ovary greatly enlarges. It attains black color with light yellow spots. Each oviduct is a long narrow and highly coiled tube. It is divided into three parts in accordance with its structure and functions.

(1) Oviducal Funnel,

(2) Oviduct and

(3) Ovisac.

The anterior end of the oviduct forms a wide and fringed oviducal funnel. The ovoiducal funnel is located on the dorsal side of the lung. The margin and inner surface of the oviducal funnel is lined by ciliated epithelium. The oviducal funnel leads into the oviduct. This oviduct is straight and thin-walled for a short distance. Thereafter it becomes highly coiled and thick-walled. This coiled oviduct runs posteriorly along the outer side of the kidney. The hinder portion of the oviduct becomes very thin walled. It is sac-like and is called ovisac. The ovisac opens of the posterior end in the dorsal wall of the cloaca by its individual apertures lying anteriorly to the openings of ureters. The cloaca opens to the exterior by a cloacal aperture at the posterior end of the body.

The release of ovum in female is termed as spawning.