Cleavage - metazoa, Biology

Cleavage - Metazoa

The unicellular zygote begins cell division (cleavage). First, the single cell divides forming two cells, these redivide further to form four, then eight cells and so on till it gets converted into a ball of cell. The cells are called blastomeres. The planes of the first and second cleavage are vertical passing through the axis, but at right angles to one another. These two cleavages together result in four blastomeres lying side by side around the axis.

The plane of the third cleavage is at right angles to the first two planes and to the axis and is horizontal and hence parallel to the equator of the zygote. This results in eight blastomeres. Of the eight blastomeres four lie on top of the other four. The pattern of cleavage and arrangement of blastomeres around an imaginary central axis in a zygote can be one of two types radial or spiral.

Posted Date: 1/15/2013 1:41:57 AM | Location : United States







Related Discussions:- Cleavage - metazoa, Assignment Help, Ask Question on Cleavage - metazoa, Get Answer, Expert's Help, Cleavage - metazoa Discussions

Write discussion on Cleavage - metazoa
Your posts are moderated
Related Questions
Q. Explain about Dry heat sterilization? It is used to sterilize glass ware, forceps, scissors, scalpels, all glass syringes, swabs, some pharmaceuticals products such as liqui

tertiary structure of protein

Domesticated animals provide much of the world's meat products today, but wildlife still constitutes to be an imp ortant source of food of many rural communities. The International

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

Osmoregulatory Animal An osmoregulatory animal is generally in an osmotic steady state even though there may be hourly and daily variations in osmotic balance. The concentrati

How are the change in the ageing lens occurred in the metabolism? Changes in the Ageing Lens 1) Physical changes: Lens weight increases, light transmission decreases, li

What is Muscle tissue explain briefly? Remember that a skin cell, in addition to the genetic information that allows it to form into a skin cell, also has all of the genetic in

Q. Explain Intraoral Barrier Techniques? Rubber dam A rubber dam is used whenever possible for improved vision and access and to reduce dental personnels' exposure to micr

Question 1 Identify the specimen, class to which it belongs and write the salient features of that class.                                               Question 2 Write

LIPOIDA L MODELS According to Overton (1902) plasma membrane consists of single layer of lipid, because cell permeability is related to lipids. According to Gorter and