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
Explain the different types of cells in cell structure ? Types of Cells :  Cells can be classified as being either prokaryotic or eukaryotic depending on whether or not a mem

as newly appointed food safety manager within a medium seized

Define Factors Affecting Energy Expenditure and Requirement? As mentioned earlier, the energy needs vary widely among individuals in a group. Why? A number of factors cause the

How would carbon monoxide poisoning affect a person's coloring, particularly of the mucous membranes? How would it affect the hemoglobin concentration, hematocrit, and percent oxyh

Define Methods of Estimation of Energy Expenditure and Requirements? There are a variety of methods available to measure human energy expenditure. Knowledge of these methods wi

Regulation of Heart The number of electrical impulses initiated by the SA node is primarily the result of its innervation by fibers from both sympathetic and parasympath

What is the gross primary production of an ecosystem? How does GPP relate to photosynthesis? Gross primary production of an ecosystem, or GPP, is the amount of organic material

Enumerate about the Mycotic Infections Invasion of the nervous system by a fungus is known as a mycotic infection. A fungus is any member of a large group of lower plants (in s

Define the Insulin resistance - Obesity? Insulin resistance is a condition in which your body cells cannot utilize insulin efficiently although sufficient amounts are secreted

Describe Alternation of Generations? Alternation of Generations :  In meiosis, four haploid daughter cells are formed from one diploid mother cell. The life cycles of sexuall