Patterns of cleavage, Biology

Assignment Help:

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


Related Discussions:- Patterns of cleavage

How does the vegetal stratification of an ecosystem, How does the vegetal s...

How does the vegetal stratification of an ecosystem influence the biological diversity? The vegetal stratification of an ecosystem, as the strata of the Amazon Rainforest, mak

Taxonomy, What category do pisces, mammalla, amphibia, reptilia and aves fa...

What category do pisces, mammalla, amphibia, reptilia and aves fall into

What is physiology root pressure explain briiefly, What is Physiology: Root...

What is Physiology: Root Pressure explain briiefly? Transport of water, minerals and nutrients within vascular plants is dramatically different from animals such as humans. Whe

Full form of hiv and aids, HIV (Human Immuno Deficiency Virus) Infection a...

HIV (Human Immuno Deficiency Virus) Infection and AIDS (Acquired Immune Deficiency Syndrome)

Define intracellular fluid or the water within the cells, Define intracellu...

Define intracellular Fluid or the water within the cells? The intracellular Fluid or the water within the cells makes up about 40-4596 of the total body weight. Because the bod

Lipoproteins help in transport of lipids, Four major groups of lipoproteins...

Four major groups of lipoproteins help in transport of lipids. These include: 1.  Chylonzicrons-function is to carry dietary triacylglycerols 2.  Very  low  density lipoprot

Ethidium bromide, Ethidium Bromide  intercalates within structure of the nu...

Ethidium Bromide  intercalates within structure of the nucleic acids in such a manner that they fluoresce under the UV light. Ethidium bromide staining is generally used to visuali

Experiment of stanley miller (1953) on the origin of life, What was the exp...

What was the experiment of Stanley Miller (1953) on the origin of life? In 1953 the Stanley Miller arranged an experimental apparatus that simulated the atmospheric conditions

Nerve cell - the basic unit, Nerve Cell - The Basic Unit The basic un...

Nerve Cell - The Basic Unit The basic unit of the nervous system is the nerve cell or neuron. A neuron is to the nervous system what a brick is to the building. It has a cell

#classification of parasitic protozoa.., most recent classification of para...

most recent classification of parasitic protozoa with its general characters

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd