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 fluids required for underweight - nutritional care, Define Fluids re...

Define Fluids required for underweight - nutritional care? Take fluids only after a meal instead of with or before meals so that food intake is not reduced. High calorie nouris

How is cancer usually treated, Q. How is cancer usually treated? If the...

Q. How is cancer usually treated? If the cancer is in its initial stage cure is often done by surgical removal of the neoplastic tissue. The Cancers already disseminated are of

Define determinants of food security - food access, Define Determinants of ...

Define Determinants of Food Security - Food Access? Food access is linked to its affordability. Food access is ensured when households and all individuals within them have adeq

What nerve is being compressed, what major nerve do you think is being comp...

what major nerve do you think is being compressed when a person often feel pain in the posterior surface of the thigh radiating to the area behind the knee and where is the likely

Morphogenesis of an ectodermal derivative, Morphogenesis of an Ectodermal D...

Morphogenesis of an Ectodermal Derivative During the development of vertebrate body the dissimilar regions in the three germ layers of the gastrula become segregated from each

Criticism of lamarckism, point out the criticism of lamarckism in any six s...

point out the criticism of lamarckism in any six short points.

Risk analysis- definiton of food, Risk analysis- Definiton of Food Food...

Risk analysis- Definiton of Food Food  :  Any  substance,  whether processed,  semi- processed  or  raw  which  is intended for human consumption, containing drinks, chewing gu

Are organic solvents like benzene and ether polar, Are organic solvents lik...

Are organic solvents like benzene and ether polar or non-polar substances? Benzene and the ethers are molecules without electrically charged portions and therefore they are non

Agro industrial-steam treatment, Steam treatment Steam treatment of cro...

Steam treatment Steam treatment of crop residues under pressure has recently opened a new vista for their nutritional improvement especially in the situation when steam availab

How did gifford pinchot view nature, How did muir's impression of man's rel...

How did muir's impression of man's relationship with nature differ from Susan Fenimore coopers? And How did Gifford Pinchot view nature?

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