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

How is the brain involved in the immune system, How is the brain involved i...

How is the brain involved in the immune system? A. Immune cells that constitute body's biological defense against infections and toxins, have many things in common with nerve c

Explain the analysis of food samples, Explain the Analysis of Food Samples?...

Explain the Analysis of Food Samples? Now, in this practical, we shall deal with the endogenous and exogeneous microorganisms which are present on the food as contaminants. We

Clinical features of tricuspid regurgitation, Q. Clinical Features of tricu...

Q. Clinical Features of tricuspid regurgitation? Patients with severe primary tricuspid regurgitation will have symptoms of fatigue, dyspnoea and effort intolerance, abdominal

What are the distinct types of proteins, Distinct types of proteins T...

Distinct types of proteins Two distinct types of proteins are known: fibrous and globular proteins. Fibrous proteins are insoluble in water and are physically tough, which

Determine the production of red blood cells, What is the substance that sti...

What is the substance that stimulates the production of red blood cells? Which is the organ that secretes it? Under what conditions does this secretion increase? The substance

Locomotion in echinodermata, Locomotion in Echinodermata Locomotion i...

Locomotion in Echinodermata Locomotion in echinoderms is accomplished through a unique canalicular system which is termed as the water-vascular system. This system is charact

Types of tissue have the greatest capacity to regenerate, Q. Which types of...

Q. Which types of tissue have the greatest capacity to regenerate? Epithelial and connective tissues have the greatest capacity to regenerate. In injuries andsmall wounds, epit

Uncomplicated q wave mi-coronary artery bypass surgery, Uncomplicated Q ...

Uncomplicated Q Wave MI :  CABG has very little place in cases of uncomplicated Q wave myocardial infarction. However the place of urgent surgery has to be compared to thrombo

State about the lengthy administration of test battery, State about the len...

State about the lengthy administration of test battery The lengthy administration of test battery may be unsuitable for some individuals (such as demented or psychiatric patien

Waste Water, Why is there a concern on waste water?

Why is there a concern on waste water?

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