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

Explain extra cardiac conduit fontan, Explain Extra Cardiac Conduit Fontan ...

Explain Extra Cardiac Conduit Fontan ? This can be done with or without cardipulmonary bypass. First step is to make a bi-directional Glenn shunt. The main pulmonary artery is

Procedures for diagnosis - isolation of etiological agent, Isolation and id...

Isolation and identification of the etiological agent: Isolation of the etiological agent is attempted in chicken embryos, cell cultures, laboratory animals, culture medi

Why is it significant that exact copies of dna, Why is it significant that ...

Why is it significant that exact copies of DNA are produced during replication? Producing exact copies make sure that when a cell divides, the offspring cells will receive the

Management goals for diverticular disease, Q. Management goals for divertic...

Q. Management goals for diverticular disease? The management goals discussed above are basic to prevention of diverticulitis. However, diet therapy during diverticulitis may b

Treatment and management of hypertension, Q. Treatment and Management of Hy...

Q. Treatment and Management of Hypertension? The first choice of treatment and management of primary hypertension is through behaviour modifications pertaining to food choices

What is the group of the phylum chordata, What is the group of the phylum C...

What is the group of the phylum Chordata that first colonized the terrestrial environment? From which habitat did they come? Amphibians, partially aquatic partially terrestrial

What are allosteric enzymes, Allosteric enzymes are those that have more ac...

Allosteric enzymes are those that have more activation center and to which other substances known as allosteric regulators bind. Allosteric regulators can be allosteric inhibito

# FUNGAL NUTRITION, Write on spoilage of food products by fungi,nutrition,c...

Write on spoilage of food products by fungi,nutrition,condition for growth,consequencies and prevention.

Pressure flow mechanism for translocation, experiments that support pressur...

experiments that support pressure flow as a mechanism for translocation

What is cholesterol, Q. What is Cholesterol? In its free, unesterified ...

Q. What is Cholesterol? In its free, unesterified form cholesterol is a major component (together with phospolipid) of cell membranes. Its presence helps to stabilize membrane

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