Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
Threshold Value of Different Larval Tissues
Threshold value of dissimilar larval tissues for the thyroid hormone concentration
One of the main problems of metamorphosis is the co-ordination of developmental events. The tail should not degenerate till some another means of locomotion, namely the limbs develop, and the gills should not regress till the animal can employ its newly developed lung muscles. Kollros (1961) illustrated the possibility of this coordination that displays that different larval tissues have diverse threshold value for thyroxine. In other words the different larval tissues are sensitive to dissimilar concentrations of thyroid hormone.
This model is termed as the threshold concept. It has been observed that structures in the tadpole that change early during metamorphosis are more sensitive to and have low threshold value to thyroxine, than those which go through transformation at a later stage. As metamorphosis commences the thyroid hormone level slowly builds up and different events occur at different concentrations of the hormone. Experimental studies have revealed that tadpole pans that have a low threshold respond earlier during metamorphoses than those parts comprising a high threshold response. In other words, the threshold value reflects the order where metamorphic changes occur in normal development. In urodeles the bulging of eyes reacts to the weakest dose of thyroid hormone (minimum threshold) and thus is the first event in metamorphosis. This is followed by reduction of fin fold and the shortening and disappearance of external gills. After which takes place the closure of gill clefts and transformation of skin.
(i) Area uses or permit exposure to radiation should be Marked' Restricted Area 'or Radiation zone etc. (ii) Avoid x-rays of chest and lower back in routine physic
Lotic Ecosystems Rivers The lotic or flowing water habitats include rivers streams, brooks etc. The most outstanding features of such habitats is the continuously flowing wat
Intermediate filaments - Role of Cytoskeleton Structures These filaments are intermediate in size among microtubules and microfilaments and are 10 nm in diameter. Five classes
Alkaline Phosphatase is an enzyme which catalyzes the hydrolysis of the phosphomonoesters of the 5' nucleotides. It is used to dephosphorylate (remove phosphate groups from) the 5
advantages of protozoa
Non-Conventional Feed Resources There are many non-traditional or non-conventional materials which are available in abundance and can form potential source of feedstuffs for f
(a) Which elements contains Carbohydrates (b) Which elements contains Proteins a) Carbohydrates contain the elements carbon , hydrogen and oxygen. b) Protei
Importance of Research in Nursing: It is the responsibility of the nursing profession to discover, verify, structure and restructure the professional knowledge through syst
What is the relationship between the estrogen level and the LH level in the menstrual cycle? What is the function of LH in the menstrual cycle and when does its blood concentration
Protozoa general characters and classification
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!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd