Patterns of cleavage, Biology

PATTERNS OF CLEAVAGE -

Patterns of cleavage depends upon amount of yolk & distribution of yolk.

These are following types -

1.       RADIAL CLEAVAGE PATTERN -

In radial cleavage the cleavage furrow cut straight through the egg at right angle to another.]

It results blastomeres appear to be arranged radially. eg. Sponge & Coelenterata.

2.       BIRADIAL CLEAVAGE PATTERN -

The cleavage furrow of first three division do not cut straight the axis of the egg.

It determine by radial symmetry in animal. eg. Ctenophora.

3.       SPIRAL CLEAVAGE PATTERN -

In this the mitotic spindle of the third cleavage in the four blatomeres are laid down obliquely and are arranged in a sort spiral.

It result four blastomeres of upper tier do not lie over the corresponding blatomeres of lower tier. eg. Annelids, moluscs, nemerteans.

Spiral cleavage is of two types -

(i) Dextral or Dextrotrophic - Blastomere rotate clockwise (i.e. right hand spiral). eg. Mollusca.

(ii) Sinistral or Levotrophic - The blastomere rotate anticlockwise (i.e. left hand coiling). eg. Flat worm, Round worm & Annelids.

4.      BILATERAL CLEAVAGE PATTERN -

In this two of the four blastomere are smaller than the other two and establish bilateral symmetry at the four cell stage. eg. Echinodermata & Chordata.

1998_cleavage pattern.png

Posted Date: 10/3/2012 8:55:53 AM | Location : United States







Related Discussions:- Patterns of cleavage, Assignment Help, Ask Question on Patterns of cleavage, Get Answer, Expert's Help, Patterns of cleavage Discussions

Write discussion on Patterns of cleavage
Your posts are moderated
Related Questions
Determine the significance of Siphuncle. A cord of tissue that passes between different chambers of a Nautilid shell. Siphuncle regulates the amount of air or fluid in chambers

How different are pteridophytes from bryophytes regarding substance transport? Pteridophytes are tracheophyte (vascular) plants, i.e., they have tissues specialized in conduct

Mutations are the only kind of variability generating mechanism in prokaryotes and asexually reproducing organisms. But in eukaryotes where sexual recombination occurs, even in one

SKI N GRAFTING - Skin for grafting is taken from another part of body of the same persons. Now it is possible to grow a sheet of skin in culture from a small piece of skin

ENERG Y TRANSFORMATION - During photosynthesis radiant energy is converted into chemical energy by green plants. In biluminiscent organisms .e.g glow worm, noctilluca &

What would happen to a cell and its offspring if the cells did not go by a G1 phase during their cell cycle? Describe Without a G1 growth phase, the cells would not grow to th

Metabolic Disorders The disease conditions, which are attributable to an imbalance between rates of input of dietary nutrients and the output of production, are defined as pro

What is Loud P2 in second heart? It occurs in pulmonary hypertension. In absence of pulmonary hypertension, it occurs when pulmonary trunk is dilated as in Ostium Secundum, ASD


Ernst Mayr, for whom, species and species problem have been the main concern of research, points out that speciation, the multiplication of species, that is division of one parent