Tadpoles of frog can be made to grow as giant sized tadpoles, if they are
administered antithyroid substance like thiourea
administered large amounts of thyroxine
reared on a diet rich in egg yolk
reared on a diet rich in both egg yolk and glucose.
A.
administered antithyroid substance like thiourea
Thyroxine, the principal hormone, of thyroid gland, is required for tissue differentiation and metamorphosis (the rapid transformation from the larval to the adult form) in amphibians. Thyroxine triggers a response from the hypothalamus, (probably by a genetic mechanism) followed by the production and release of TSH (Thyroid stimulating hormone), thus metamorphosis begins and tadpoles metamorphose into frogs. Thiourea is an organic compound of carbon, nitrogen, sulphur and hydrogen, with the formula CSN2H4, or (NH2)2CS. It is similar to urea, except that oxygen atom is replaced by a sulphur atom.
