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

Protoplast, PROTOPLAST Cell without cell membrane (Henstein) It c...

PROTOPLAST Cell without cell membrane (Henstein) It contains 1 or more vacuoles. In mature plant cells protoplast forms a peripheral layer called Primordial utricle.

Zoonoses disease-monkey pox, Monkey pox Monkey pox is caused by Monkey pox...

Monkey pox Monkey pox is caused by Monkey pox virus, a member of genus Orthopoxvirus. Transmission generally occurs as a result of close contact with infected animals, mostly thro

Dietary management for ulcerative colitis, Q. Dietary Management for ulcera...

Q. Dietary Management for ulcerative colitis? Proper dietary management is important for maintaining a good nutritional status of the patient. Long-term management is generally

Explain the both sex-linked trait and a sex-influenced trait, Explain the d...

Explain the difference among a sex-linked trait and a sex-influenced trait. A sex-influenced trait is influenced by the presence of sex hormones and its genes are not situated

Fast response - biological responses, Fast Response - Biological Responses ...

Fast Response - Biological Responses Some of the fast responses are discussed below: It was found that when mung bean root tips were kept in a specific solution (contain

Codeine, CODEIN E - It is methylmorphine, obtained from opium. I...

CODEIN E - It is methylmorphine, obtained from opium. It is used in cough syrups. A notable side effect of codeine is constipation.

Angiosperm, What is morphological nature of angiosperm

What is morphological nature of angiosperm

Determine about the scales developed by golden, Determine about the scales ...

Determine about the scales developed by golden Several other scales have been developed by Golden and various collaborators, all of which are based on different ways of scoring

What are the types of cell respiration, What are the types of cell respirat...

What are the types of cell respiration? There are two types of cell respiration: aerobic cell respiration, a reaction with participation of molecular oxygen (O2), and anaerobic

Explain cidofovir, Cidofovir (Vistide) IV cidofovir given once weekly ...

Cidofovir (Vistide) IV cidofovir given once weekly for 2 weeks and then once every 2 weeks for maintenance therapy can delay progression of CMV retinitis in patients with AIDS

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