The active biological process by which an organism produces its own kind of individual is called reproduction.
Frog is an unisexual animal and shows sexual dimorphism. It reproduces only sexually and having external fertilization.
Its reproductive system can be studied under two headings:-
The reproductive system of female frog remains completely separated from its excretory system. The female reproductive system of frog consists of following structures:-
It is a primary reproductive organ of female frog.
There is a pair of irregular shaped ovaries attached to the kidney a fold of peritoneum is called mesovarium. It is a multilobed hollow sac grayish or, blackish in colour.
In breeding season, the two ovaries become greatly enlarged and cover whole body cavity.
Ovary of frog remains surrounded by connective tissue which is lined by a layer of germinal epithelial cells.
The cells of germinal epithelial cells form ovum by oogenesis. So, ovary contains ovum in different developing stage. After maturation ovum is released by rupture of ovarian wall into the body cavity from where they are moved and stored in uterus or, ovisac by cilia of peritoneum into the ostia of oviducts.
On either side of body cavity long and much coiled white glandular tubes called oviducts. These are not connected directly to ovaries. Each oviducts open at the anterior part of body cavity between lung and liver by a ciliated funnel like structure called ostium.
The glandular cells of oviduct secrete albumen which forms a covering around ovum during its passage in the oviduct.
The posteriormost part of each oviduct swells to form a thin walled ovisac or, uterus. These open dorsally into cloaca separately on papillae just in front of the apertures of uterus.
Ovisac stores the ovum which is ready to fertilize.
The release of ovum from ovisac during mating is called spawning and the group of ova is called spawn.