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

Animal and plant cells, Animal and Plant Cells The internal structural ...

Animal and Plant Cells The internal structural organisation and information related with hereditary characters and metabolic pathways are similar in all eucaryotic cells whethe

Control of air pollution, Air pollution can be controlled by two fundamenta...

Air pollution can be controlled by two fundamental ways. Preventive technique: Important measure to control air pollution Suitable fuel having low sulphur content shoul

Why do substances react with each other, Why do substances react with each ...

Why do substances react with each other? Chemical reactions occur due to the products of the reaction have less energy than the reactants (drive toward less energy). These reac

Biotechnology... what is the answer/, At a biotechnologist, employment oppo...

At a biotechnologist, employment opportunities can be found in many areas. In addition to biotechnology companies, where can a scientist with a biotechnology background find employ

5.4 assessment from the book, Briefly explain why cutting a flatworm into p...

Briefly explain why cutting a flatworm into pieces would not kill it

Describe asd closure and vsd closure in heart dieases, Describe ASD closure...

Describe ASD closure and VSD closure in heart dieases? ASD Closures : Small ASD's can be closed directly. Others will need a pericardial patch. Piimum ASD and Sinus Venosus A

Chemotaxis - modes of cell movement, Chemotaxis - Modes of Cell Movement ...

Chemotaxis - Modes of Cell Movement Chemotaxis considers to me directed movement of cells in response to a concentration gradient of a chemical factor in solution. An instance

Phases of water, Phases of Water The state of water can be changed from...

Phases of Water The state of water can be changed from gaseous to liquid and liquid to solid and vice versa by the addition or removal of heat energy. To convert one gram of li

Carrier protein in a plasma membrane, What is a characteristic feature of a...

What is a characteristic feature of a carrier protein in a plasma membrane? Carrier proteins are globular proteins which are particular it their action and therefore regulate t

How could an adult lose billions of cells, How can an adult lose billions o...

How can an adult lose billions of cells from all parts of the body each day and still survive?

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