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
Q. Explain the Rapport Building? Maintaining good relationship with the client is very important in counselling. This will help you to gain trust, confidence of the client and

What characteristics of fatty acids are false? (Dissolves in water, used for energy storage, used to build lipids, found in triglycerides, found in steroids)?

If NAD+ is an electron acceptor that becomes NADH and the NADH then donates a proton to ATPase, shouldn't NADH now become NAD- since it lost it's proton but still has the electron?

What is the meaning of Oedema? In some pathological conditions the body is in a positive water balance; that is the intake of fluids is greater than the excretion, and the pati

A calico female has a litter of kitten which includes several calico females a yellow male a couple of yellow females and two black males what is the likely color of the father and

Cnidaria and Platyhelminthes - Larval forms Cnidaria The common larval stage that is found in cnidarians is the planula which forms following gastrulation. The planula is

Define Dietary Management during Surgery? Surgery increases the nutritional demands of the body and can lead to the elicitation of several nutritional deficiencies/imbalance. M

FUNCTIO N OF LIPIDS Fats are storage products of both plants and animals. I n plants , fats are commonly stored in spores and seeds while in animals they are sto

What is the type of digestion that occurs in cnidarians? These animals have a digestive cavity and they make intracellular and extracellular digestion. The extracellular digest