Types of cleavage, Biology

Assignment Help:

Types of Cleavage

a) Radial Type: If each of the blastomeres of upper tier lies exactly over the corresponding blastomeres of the lower tier the pattern of cleavage is radially symmetrical i.e. blastomeres are arranged along the radii of the sphere, e.g. echinoderms, Amphioxus, amphibians.

b) Spiral Type: The upper tier of blastomeres of 8-cell stage embryo may be shifted with respect to the lower tier so that radially symmetrical arrangement of blastomeres is distorted in various degrees. In such a case the blastomeres of the upper tier do not lie exactly over the corresponding blastomeres of the lower tier.

Instead, all the blastomeres of upper tier are shifted in the same direction with respect to all the blastomeres of the lower tier. This position results from the oblique position of mitotic spindle so that, from the start, two daughter blastomeres do not lie one above the other, e.g., annelids, molluscs, some helminths of order polycladida.


Related Discussions:- Types of cleavage

Meat product quality assurance, P r o d u c t Quality Assurance M...

P r o d u c t Quality Assurance Meat products should be manufactured under strict hygiene and sanitary conditions to avoid public health risks and improve aesthetic appea

Structure of water, STRUCTURE OF WATER It may interest you to know that w...

STRUCTURE OF WATER It may interest you to know that water is a universal solvent and is a major constituent of all living organisms. Earth is the only planet where water exists i

Describe the basic working of chemoreceptors, Q. Where are the chemorecepto...

Q. Where are the chemoreceptors that detect the acidity of the trigger and blood the respiratory compensation located? The chemoreceptors that participate in the ventilation co

Coelenterata, is cnidaria having both interacellular & extracellular digest...

is cnidaria having both interacellular & extracellular digestion?

Sexual reproduction, SEXUAL REPRODUCTION You must be aware that reproduct...

SEXUAL REPRODUCTION You must be aware that reproduction is one of the distinguishing features of living beings. Reproduction is basically of two types: asexual and sexual. In ase

Determine the parts of stethoscope, Determine the Parts of Stethoscope ...

Determine the Parts of Stethoscope A stethoscope having of earplugs, binaural pieces, flexible tubing, a stem, and a chest piece. The earplugs are attached to springs made of s

Examination of the prosthesis, Examination of the Prosthesis It is impo...

Examination of the Prosthesis It is important to examine the prosthesis thoroughly.  This involves assessing mobility, checking screws, evaluating attachments and porcelain res

How to investigate mitral regurgitation by electrocardiogram, Q. How to Inv...

Q. How to Investigate mitral regurgitation by Electrocardiogram? Patients with severe mitral regurgitation often have atrial fibrillation. Left atrial enlargement is a common f

Explain about low blood sugar, Q. Explain about Low blood sugar? Low bl...

Q. Explain about Low blood sugar? Low blood sugar can also be caused by accidentally taking too much of insulin. When this occurs, more insulin is present in the body than nee

Cori cycle, Cori Cycle Skeletal muscles have some mitochondria, yet are...

Cori Cycle Skeletal muscles have some mitochondria, yet are competent of vigorous activity. as a output, the little stores of oxygen are rapidly depleted, causing the muscle ti

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