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 detail about the golgi bodies, Explain detail about the Golgi Bodie...

Explain detail about the Golgi Bodies Eukaryotic cells possess, within the cytoplasm, a complex organisation of a cluster of membrane-surrounded vesicles called the Golgi bodie

What is the definition of ecology explain, What is the Definition of Ecolog...

What is the Definition of Ecology explain? Scientists use the term ecology to refer to the study of the relationships between organisms, and the relationships between organism

Explain the basic concept of energy, Explain the basic Concept of Energy? ...

Explain the basic Concept of Energy? Energy in simple terms may be defined as the ability, or power, to do work. As a student of dietetics and nutrition, you already know that

What is archaebacteria, What is Archaebacteria ? Archaebacteria is a re...

What is Archaebacteria ? Archaebacteria is a relatively new grouping that was created in the light of relatively recent biochemical and electron microscopic evidence. These fin

Acetylcholine - long term potentiation, Acetylcholine, a well known neurotr...

Acetylcholine, a well known neurotransmitter, plays a critical synaptic role in the initial formation of memory. Chemical blockage of the acetylcholine receptors makes it harder to

Carbohydrate required for underweight - nutritional care, Explain the Carbo...

Explain the Carbohydrate required for underweight - Nutritional Care? Liberal amounts of easy to digest carbohydrates should be included in the diet. The intake of dietary fibr

Strategie of the anti-retroviral drug used in aids treatment, Q. What are s...

Q. What are some strategies of the anti-retroviral drugs used in the AIDS treatment? The Anti-retroviral drugs used in AIDS treatment try to approach any of the several steps o

Zoonoses disease-erysipeloid, Erysipeloid A zoonosis called erysipelas ...

Erysipeloid A zoonosis called erysipelas in animals, rose disease in pig, erysipaloid in man is caused by Erysipelothrix rhusiopathiae (insidiosa). Other names given to this co

Parasitic adoptaion in animal, #question.what do u mean by parasitic habit....

#question.what do u mean by parasitic habit.give account of various parasitic adoptation in animal.

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