Mosaic and regulative eggs, Biology

Mosaic and Regulative Eggs

Eggs as well as early cleavage embryos are occasionally divided into two categories:

i) Mosaic or determinate embryos and

ii) Regulative or indeterminate embryos.

The terms mosaic and regulative relate to the time for which the restrictions in development are imposed on the blastomeres. For instance, the embryos of tunicates related to mosaic or determinate category. In these organisms the various blastomeres become restricted to make only specific structures as soon as they are formed or during the first few cleavages. In other words, the respective fates of dissimilar blastomeres are finally determined early in mosaic embryos. As a result, the removal or loss of specific blastomeres cannot be compensated by the other blastomeres and the embryos will be defective in structures that are normally derived from the missing blastomeres.

In regulative or indeterminate embryos the restrictions on blastomeres take place later in development. Amphibians and sea-urchins belong to this category. Because the cell fate of blastomeres is lastly determined later, any removal or destruction of blastomeres early in development can be compensated by the other blastomeres that are able to form all the structures. It is also believed that the differences between mosaic and regulative embryos are directly connected to the extent of their usage of extrinsic and intrinsic mechanisms for cell determination. The mosaic embryos depend on ooplasmic determinants, i.e. intrinsic factors for cell fate determination. In contrast, the regulative embryos mostly rely upon extrinsic factors derived from cell interaction for cell determination.

Posted Date: 1/29/2013 12:16:25 AM | Location : United States







Related Discussions:- Mosaic and regulative eggs, Assignment Help, Ask Question on Mosaic and regulative eggs, Get Answer, Expert's Help, Mosaic and regulative eggs Discussions

Write discussion on Mosaic and regulative eggs
Your posts are moderated
Related Questions
Define Health and Feeding Problems among Elderly? Malnutrition, both obesity and under nutrition, are common problems linked with elderly.  Some of the common disorders such as

Self-Monitoring of Blood Glucose (SMBG) In SMBG, patients measure and monitor their blood sugar level by themselves and assess their condition and know the response to the trea

A few simple tips which should be given to the patient. • Boiling, steaming, baking, pressure cooking should be encouraged • Consume small and light meals frequently instea

Q. What are some strategies of the anti-retroviral drugs used in the AIDS treatment? The Anti-retroviral drugs used in AIDS treatment try to approach any of the several steps o

Q. What are the zymogens? proenzymes, or Zymogens, are enzymes secreted in inactive form. Under some conditions a zymogen shifts to the active form of the enzyme. Zymogen secre

Egg - Synergids The three cells of the egg apparatus are arranged in triangular fashion with the egg sharing a common wall with the two synergids and the central cell. In the

1. DNA damaga can be spontaneous or can be 'Induced by external agents a. What are 'spontaneous' mutations? Give examples of causes of spontaneous mutations and the kinds od DNA

What is the genetic code? Genetic code is the key for the conversion of DNA nucleotide sequences (and therefore RNA nucleotide sequences) into amino acids sequences that will c

Why do we need a family of proteins for cell adhesion (what is the advantage of having a family of proteins?)

A haploid cell contains: A.one half of a complete set of chromosomes B.several complete sets of chromosomes C.the correct number of chromosomes D.two complete sets of chromosomes E