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

What is biotechnology, What is biotechnology? Biotechnology is the appl...

What is biotechnology? Biotechnology is the application of biological knowledge to get new techniques, materials and compounds of pharmaceutical, medical, agrarian, industrial

Catalogue of larval forms in various animal groups, Catalogue of Larval For...

Catalogue of Larval Forms in Various Animal Groups The larval stages and types found in different groups are many. Each larval type has a different structure and is known by a

Excretion in roundworm, EXCRETIO N IN ROUNDWORM - In ascaris 4 coelomo...

EXCRETIO N IN ROUNDWORM - In ascaris 4 coelomoducts present, attached to each other by canaliculli in front of controling cell i.e. Rennete cell. Excretion materials are gi

Protozoa, What is meant by encystment

What is meant by encystment

What are the three main limiting factors of photosynthesis, What are the th...

What are the three main limiting factors of photosynthesis? The three major limiting factors of photosynthesis process are light intensity, carbon dioxide concentration and tem

Show the parameters which are of interest in chd, Q. Show the parameters wh...

Q. Show the parameters which are of interest in CHD? Total Cholesterol: Serum totnl cholesterol equals the sum of HDL-cholesterol (HDL-c), VLDL-cholesterol (VLDL-c) and LDL-cho

What happen when a fatty acid reacts with glycerol, When a fatty acid react...

When a fatty acid reacts with glycerol, the result is- Select one: a. Formation of an amide b. Formation of an ester c. Formation of hydrocarbon d. Formation of a th

Describe cluster analysis, Q. Describe Cluster analysis? After making a...

Q. Describe Cluster analysis? After making a similarity table, it is then rearranged so that OTU's whose members have the highest mutual similarity are brought together. This c

Joints, JOINTS - The structural arrangement of tissues which connect 2 ...

JOINTS - The structural arrangement of tissues which connect 2 or more bones together at their place of meeting is called a joint. Study of joint is arthrology. Joint make 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