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

Name the two groups of nephrons, Name the two groups of nephrons on the bas...

Name the two groups of nephrons on the basis of their position in the kidney. How are they different from each other? a) How is the halophyte Rhizophora adapted to survive in i

State normal physiological saline, A complete motor neuron is deleted from ...

A complete motor neuron is deleted from a frog and placed in a large volume of normal physiological saline.  The neuron is healthy; it has a stable resting voltage of -70 mill

Explain the regulation of breathing and blood pressure, Which is the brain ...

Which is the brain region responsible for the regulation of breathing and blood pressure? The neural regulation of breathing, blood pressure and other physiological parameters

Difference between the concepts of karyotype and genome, Normal 0 ...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

Why is it rare to find hemophilic women, Why is it rare to find hemophilic ...

Why is it rare to find hemophilic women? There are less hemophilic women than hemophilic men because women need to have two X chromosomes affected to develop the disease while

Direct approach to counseling, Q. Direct Approach to counseling? The di...

Q. Direct Approach to counseling? The direct approach to counselling is also called as the problem-solving approach. The counsellor collects relevant information which aims to

Define features of fusarium - fungi and yeast, Define features of Fusarium ...

Define features of Fusarium - Identification of Fungi and Yeasts? Identifying features of Fusarium: 1. Wooly, white fuzzy colonies changing colour to pink, purple or yellow.

Explain the composition of macconkey agar, Explain the Composition of MacCo...

Explain the Composition of MacConkey Agar? Bactopeptone - 17.0 gm Protease Peptone - 3.0 gm Lactose - 10.0 gm Bile salt mixture - 1.5 gm Sodium chloride - 5.0 gm

Describe the process of crassulacean acid metabolism, Describe the process ...

Describe the process of Crassulacean acid metabolism. a) How is it advantageous to plants? b) Describe the major steps in Krebs cycle. Why is this cycle also called citric a

Wind as a medium for dispersal, Wind as a medium for Dispersal Many mic...

Wind as a medium for Dispersal Many microorganisms, fungal spores and bacteria are freely transported over long distances even by moderate winds. In wind pollinated plants, the

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