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

Homework, Which of the following is NOT a process that may provide an adapt...

Which of the following is NOT a process that may provide an adaptive advantage to eukaryotic chromosomes?.tion..

Epidemiology of plague, Question 1 A patient is admitted to the hospital w...

Question 1 A patient is admitted to the hospital with suspected pneumococcal pneumonia. How would you confirm this initial diagnosis? Answer the following questions a) Which is

Inorganic nitrogen and sulphur metabolism, Inorganic Nitrogen and Sulphur M...

Inorganic Nitrogen and Sulphur Metabolism Productivity in agriculture, forestry and other ecosystems is basically limited by the availability of nitrogen nutrients like nitrat

Define carbohydrates needs in postoperative nutritional care, Define Carboh...

Define Carbohydrates needs in Postoperative Nutritional Care? Carbohydrates ensure the use of protein for tissue synthesis and energy required for increased metabolic demands.

Subatomic Particles, We have end of semester exams coming up meaning that a...

We have end of semester exams coming up meaning that a majority of it will be over subatomic particles

What are the result of arterial switch operation, What are the result of Ar...

What are the result of Arterial Switch operation ? The operation is highly specialised. When carried out in experienced centers the mortality for simple TGA and TGA with VSD i

Define about the zinc deficiency, Define about the Zinc Deficiency? Evi...

Define about the Zinc Deficiency? Evidence suggests that nearly one-third of preschool children in lower-income countries have stunted growth, and that a considerable proportio

Importance of family and patient education - food allergy, Define Importanc...

Define Importance of Family and Patient Education - Food Allergy? Remember, involvement of the family and all other relevant caretakers along with the patient is crucial for pr

Explain procambium in primary growing shoot, Explain Procambium in primary ...

Explain Procambium in primary growth in shoot ? The vascular tissue in the shoot is produced from a primary tissue called the procambium, located in the apical meristem. New vas

Phylum protozoa, distinguishing charecters and classification of protozoa u...

distinguishing charecters and classification of protozoa upto phyla

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