GENERAL HISTOLOGY

Detailed explanation-1: -Metamorphosis of the tadpole larva into an adult frog is one of the most striking transformations in all of biology (Figure 2.4). In amphibians, metamorphosis is initiated by hormones from the tadpole’s thyroid gland, and these changes prepare an aquatic organism for a terrestrial existence.

Detailed explanation-2: -Like beautiful butterflies, frogs and toads undergo an astonishing transformation – which is called ‘metamorphosis’ – as they grow up. From jelly-like eggs laid in water, they grow into wriggling tadpoles, and finally grow legs suitable for land!

Detailed explanation-3: -At first, the tadpoles do not look like adult frogs. Unlike most animal species, frogs, like some other amphibians, have a larval state and then must undergo metamorphosis to enter into the adult phase of their life cycle. It is not until they have gone through metamorphosis that the tadpoles really look like frogs.

Detailed explanation-4: -A female frog lays eggs in the water, which are fertilized by sperm from a male frog. The resulting zygote goes through embryonic development to become a free-living tadpole, which then metamorphoses into an adult frog-for instance, by losing its tail through programmed cell death, or apoptosis.

Detailed explanation-5: -As the tadpole grows, hind limbs emerge, and they soon begin to look like small frogs with tails. They also begin to develop lungs, so they can breathe out of the water when they begin to spend time on land. Skin then forms over the juvenile gills to reveal a juvenile frog with a very long tail!