Female reproductive system consists of two ovaries and two oviducts.
1.Ovaries: A pair of ovaries are present. Each ovary is attached to the kidney by a double fold of peritoneum called as mesovarium. It is a large, irregularly folded, multilobed, hollow sac grayish or blackish in colour. It's size varies in different seasons. In breeding season, the two ovaries become greatly enlarged.
Histologically, each ovary contains number of hollow lobules. Each lobule remains lined by germinal epithelium. The cells of germinal epithelium undergo the process of oogenesis to form egg or ovum. Innumerable dark round ova in different stages of development are present inside ovaries. When ripe, the ova are shed by rupture of ovarian wall into the body cavity from where they are moved by cilia of peritoneum into the ostia of oviducts. Fat bodies are also attached in front of ovaries which provide reserve food to nourish developing egg and during hibernation.
2. Oviducts: The two oviducts are long and much coiled white glandular tubes not connected directly to the ovaries. Their anterior ends form ciliated funnel-like openings, the ostia (Singular: Ostium). These are placed quite anteriorly in the body cavity at the bases of lungs one on either side of oesophagus. These ostia receive eggs from body cavity. The Cilia present on the inner walls of oviduct move the egg posteriorly while glands secrete an albuminous coat around each egg during its passage. The posterior ends of oviducts open dorsally into cloaca separately on papillae just in front of the apertures of ureters. Just before entering cloaca, each oviduct forms a thin walled enlargement, the ovisac. The eggs are collected inside ovisacs before being laid.
Structure of egg:
An unfertilized ripe egg of frog is spherical in shape. Its upper black pigmented half containing nucleus and cytoplasm is called animal hemisphere. The lower whiter half containing yolk is called vegetal hemisphere. The amount of yolk in egg is called as lecithality. As Frog's egg contains moderate amount of yolk, it is called as mesolecithal egg. However, whole yolk remain concentrated in posterior half so it is called as telolecithal egg. It is radially symmetrical. Around the egg is a two-layered vitelline membrane of its own secretion. The outer albuminous coat on contact with water swells into a thick jelly like layer which probably prevents over crowding and protects from infections and predators.
Reproduction:-
Breeding season of frog is rainy season from June to September. The male frog produces croaking sound to attract females. The male mounts on the back of female frog and presses her abdomen with the help of fore limbs. The Copulatory pad prevents male from slipping. This sexual embrace is called as amplexus. It takes place in water and during it eggs are passed out through cloacal aperture. The male sprays sperms over egg.
The albuminous covering of egg swells up and become sticky in water. Thus, a number of eggs get attached with each other forming mass of egg called as spawn.
Fertilization is external & takes place in water. The development is indirect with free-living aquatic tadpole larva.
1.Ovaries: A pair of ovaries are present. Each ovary is attached to the kidney by a double fold of peritoneum called as mesovarium. It is a large, irregularly folded, multilobed, hollow sac grayish or blackish in colour. It's size varies in different seasons. In breeding season, the two ovaries become greatly enlarged.
Histologically, each ovary contains number of hollow lobules. Each lobule remains lined by germinal epithelium. The cells of germinal epithelium undergo the process of oogenesis to form egg or ovum. Innumerable dark round ova in different stages of development are present inside ovaries. When ripe, the ova are shed by rupture of ovarian wall into the body cavity from where they are moved by cilia of peritoneum into the ostia of oviducts. Fat bodies are also attached in front of ovaries which provide reserve food to nourish developing egg and during hibernation.
2. Oviducts: The two oviducts are long and much coiled white glandular tubes not connected directly to the ovaries. Their anterior ends form ciliated funnel-like openings, the ostia (Singular: Ostium). These are placed quite anteriorly in the body cavity at the bases of lungs one on either side of oesophagus. These ostia receive eggs from body cavity. The Cilia present on the inner walls of oviduct move the egg posteriorly while glands secrete an albuminous coat around each egg during its passage. The posterior ends of oviducts open dorsally into cloaca separately on papillae just in front of the apertures of ureters. Just before entering cloaca, each oviduct forms a thin walled enlargement, the ovisac. The eggs are collected inside ovisacs before being laid.
Structure of egg:
An unfertilized ripe egg of frog is spherical in shape. Its upper black pigmented half containing nucleus and cytoplasm is called animal hemisphere. The lower whiter half containing yolk is called vegetal hemisphere. The amount of yolk in egg is called as lecithality. As Frog's egg contains moderate amount of yolk, it is called as mesolecithal egg. However, whole yolk remain concentrated in posterior half so it is called as telolecithal egg. It is radially symmetrical. Around the egg is a two-layered vitelline membrane of its own secretion. The outer albuminous coat on contact with water swells into a thick jelly like layer which probably prevents over crowding and protects from infections and predators.
Reproduction:-
Breeding season of frog is rainy season from June to September. The male frog produces croaking sound to attract females. The male mounts on the back of female frog and presses her abdomen with the help of fore limbs. The Copulatory pad prevents male from slipping. This sexual embrace is called as amplexus. It takes place in water and during it eggs are passed out through cloacal aperture. The male sprays sperms over egg.
The albuminous covering of egg swells up and become sticky in water. Thus, a number of eggs get attached with each other forming mass of egg called as spawn.
Fertilization is external & takes place in water. The development is indirect with free-living aquatic tadpole larva.