Hormones in metamorphosis of amphibia, Biology

Assignment Help:

Hormones in Metamorphosis of Amphibia

In amphibians, the changes that take place during metamorphosis are brought about by hormonal secretions of the thyroid gland. The first sign of this was obtained in 1912 when Gudematsch reported that frog tadpoles while fed dried and powdered sheep thyroid underwent precocious or early metamorphosis. Identical results however were not observed when tadpoles were fed along with preparation of other glands. These experiments made it feasible to postulate that thyroid hormones bring about metamorphosis.

In 1918 B.M. Allen observed that elimination of thyroid rudiment from early frog tadpoles, prevented them from going through metamorphosis, and caused them to become giant tadpoles instead. Conversely, if they were fed with thyroid or immersed in water containing soluble extracts from thyroid glands they then proceeded immediately to metamorphosis. Identical experiments in urodele amphibians, in particular in axolotl, Ambystoma mexicanum, also indicated the significance of the thyroid gland in urodele metamorphosis.


Related Discussions:- Hormones in metamorphosis of amphibia

How antigen react against future infection by same agent, Q. How can an org...

Q. How can an organism that once underwent contact with an antigen be immunized against future infections by the same agent? This phenomenon is called as immune memory when an

Define the energy requirement to avoid underweight problem, Define the Ener...

Define the Energy requirement to avoid Underweight problem? The total calorie intake should be 500 to 1000 Kcal in excess of the daily needs in order to result a gain in weight

Define nutrition screening initiative (nsi), Define Nutrition Screening Ini...

Define Nutrition Screening Initiative (NSI)? (NSI) tries to identify basic risk factors - inappropriate food intake, poverty, social isolation, disability, acute / chronic dise

Give a specific example for epithelial, PROVIDE a specific example for epit...

PROVIDE a specific example for epithelial and connective tissues, how the arrangement of cells helps with tissue functioning?

Under which environments do echinoderms live, Q Under which environments do...

Q Under which environments do echinoderms live? Echinoderms are marine animals and they live in salt water.

Illustrate the term cilia, Illustrate the term Cilia? A cellular hairli...

Illustrate the term Cilia? A cellular hairlike locomotory structure which comprises an extension of the plasma membrane surrounding a 9+2 organization of microtubules. Unlike f

What is nagel''s anomaloscope, What is Nagel's Anomaloscope The patient...

What is Nagel's Anomaloscope The patient is asked to match a yellow with a mixture of red and green wave lengths. A defect can be detected based on the amount of red and green

Define the uremia and nitrogen disposal, Define the Uremia and Nitrogen Dis...

Define the Uremia and Nitrogen Disposal? In animals, faecal and renal nitrogen were enhanced and decreased uremia was seen in normal and nephrectomised animals. The mechanisms

Define isolated soybean proteins in infant formulas, Define isolated soybea...

Define isolated soybean proteins in Infant formulas? Infant formulas, where milk solids have been replaced by soy products, are well established commercial products. ISP is the

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd