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

Explain the objective of cardiac rehabilitation, Explain the OBJECTIVE of C...

Explain the OBJECTIVE of Cardiac Rehabilitation ? After going through this unit, you should be able to: 1 identifies the eligible candidate for cardiac rehabilitation and be

What is pulmonary embolism surgery indications, What is Pulmonary Embolism ...

What is Pulmonary Embolism Surgery Indications ? Indications for Surgery :  Acute pulmonary embolism with haemodynamic instability and hypoxaemia is nearly always fatal. Mor

Explain about the lipoproteins, Explain about the Lipoproteins? These a...

Explain about the Lipoproteins? These are the Multicomponent complexes of lipids and proteins that form distinct molecular aggregates. They contain polar and neutral lipids, ch

What is the major cell organelle involved in cell digestion, Q. What is the...

Q. What is the major cell organelle involved in cell digestion and what are the properties of that organelle that enable it to do the task? The organelles accountable for intra

What does radial symmetry mean, What does radial symmetry mean? What is the...

What does radial symmetry mean? What is the type of symmetry found in chordates? Which are other phyla of the animal kingdom that present species with radial symmetry? Radial

Processing methods for amelioration of anti-nutritional , Processing Method...

Processing Methods for Amelioration of Anti-Nutritional Meals from many oil seeds often contain undesirable toxic and allergenic compounds that can reduce their nutritive valu

Renal glycosuria and self monitoring of blood glucose, Renal Glycosuria ...

Renal Glycosuria Renal glycosuria is a condition in which the glucose is excreted in the urine in spite of normal blood sugar levels. Self Monitoring of Blood Glucose (SMBG

Thermal fluctuations and bonds, The stabilization energy of a bond or inter...

The stabilization energy of a bond or interatomic interaction is the change in energy upon breakage of a bond between two atoms (i.e., the change in energy when the atoms are moved

Harshey-chase experiement, What is the Harshey-chase experiement .explain i...

What is the Harshey-chase experiement .explain in detail

What is post myocardial infarction ventricular septal defect, What is Pos...

What is Post Myocardial Infarction Ventricular Septal Defect ? Post Myocardial Infarction Ventricular Septal Defect (Septal Rupture) The correct terminology is septal

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