Primary egg envelopes, Biology

Assignment Help:

Primary Egg Envelopes

These are the egg envelopes which develop in the ovary between oocyte and follicle cells in the space occupied by the interdigitating microvilli. Such envelopes have been named variously in different animals.

a) It is named as vitelline envelope or vitelline membrane in insects, molluscs, amphibians and birds.

b) In tunicates and fishes, it is known as chorion. In many sharks and bony fishes the primary envelope has striated appearance and is referred to as zona radiata representing the degraded microvilli of the growing oocyte. The perforation in the zona radiata becomes the micropyle through which the spermatozoa can enter the egg.

c) In mammals, the unstriated and modified zona pellucida is formed as a result of joint efforts of egg and follicle cells. While escaping the Graafian follicle mammalian oocyte carries on the surface of zona pellucida a layer of follicle cells known as corona radiata. The primary envelopes usually stick closely to the egg surface. These later on participate in the formation of fertilization membrane.


Related Discussions:- Primary egg envelopes

Define resistant starch from the physiological perspective, Define Resistan...

Define Resistant Starch From the physiological perspective? RS is defined as the sum of starch and products of starch degradation not absorbed in the small intestine of healthy

Classification of hypertension, Q. Show basic Classification of hypertensio...

Q. Show basic Classification of hypertension? Unlike many other diseases, hypertension develops insidiously (without symptoms). In 90% of hypertension cases, the cause is unkn

Define typical structures of the seed and define endosperm, What are typica...

What are typical structures of the seed? What is the endosperm? A typical seed is the composed of the embryo, endosperm and shell. Inside seeds of angiosperms there are one or

What are pleura, What are pleura, pericardium and peritoneum? Pleura ar...

What are pleura, pericardium and peritoneum? Pleura are the membrane that hides the lungs and the inner wall of the chest; pericardium is the membrane that hides the heart; per

B -pleated sheets protein structure, β - Pleated Sheets In this in...

β - Pleated Sheets In this inter molecular hydrogen bonds are present Two or more polypeptide chains come together and from a sheet. Condensation in little. However

Define needle selection for suturing, Define Needle selection for Suturing ...

Define Needle selection for Suturing 1. Needle with a reverse cutting edge "the cutting edge is outside the curve" is preferable, because it prevents tearing, 2. Conventiona

Macro µ nutrients, Tabulate macro & micro nutrients on the basis of -...

Tabulate macro & micro nutrients on the basis of -elements, source, synthesis site, symptoms

Give the results of distae dissection , Give the results of DistaE Dissecti...

Give the results of DistaE Dissection ? Results :  For acute dissection of different parts of aorta, the mortality is reported as 9 to 33 per cent. In the International Regis

Why is pattern baldness more common in men than in women, Why is pattern ba...

Why is pattern baldness more common in men than in women? Pattern baldness is handled by the allele B. Testosterone interacts with the heterozygous genotype (BB′) to make baldn

Define fluids requirement to avoid underweight problem, Define Fluids requi...

Define Fluids requirement to avoid underweight problem? Take fluids only after a meal instead of with or before meals so that food intake is not reduced. High calorie nourishin

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