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
CHEMICA L COMPOSITION OF CHROMATIN Chromatin threads composed of DNA (31 %), RNA (2-5%) and proteins (Histon-36%, Non histon 28%). Histone and protamines are basic prote

Define Reagents required and Methodology for Fehling's Test? - Sugar solutions of glucose, fructose, galactose, lactose, maltose, sucrose, starch - Fehling A (Copper sulphat

Explain the Scanning Electron Microscope It can be used to observe intact cells or cell components directly. Then sections are not necessary. It is used for visualizing surface

List out the endothermic and exothermic reactions taking place in our body

Importance of cellulose About one third of the world's production of  purified cellulose is  used as the base material for a number of water-soluble derivatives with predesigne

While  various  positive  control  components  lie  close  to the  gene  they  regulate additional can be situated long distances away (sometimes 10-50 kb) either upstream or downs

Evidence  Similarities between 79° and 70°, eg Feeding activity continuous / continues for 24 hours during polar day (summer months) feeding activity more intense i

1- Describe the function of enzymes in catalyzing biological reactions ? 2-Descride enzymes ' role in reducign activation energy?

a) The elongation level of translation in eukaryotes requires three elongation factors, eEF-IB, eEF-1A and eEF-2, that have similar functions to their prokaryotic counterparts EF-G

Explain the effect on Vitamins of the human milk? Although there are inter-individual variations in vitamin concentrations, diet and drug use by individual women influences vit