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 about bt reassessment, Will the plant-incorporated protectants rule...

Will the plant-incorporated protectants rules affect the Bt reassessment? No. To make sure that our biotechnology assessments reflect the latest data on health and ecological e

Explain the coenzyme in enzyme catalyzed reactions, Explain the Coenzyme in...

Explain the Coenzyme in enzyme catalyzed reactions? Thiamin functions as the coenzyme thiamin pyrophosphate (TPP) in the inetabolism of carbohydrates and branched- chain amino

Anatomy in relation to taxonomy, Q. Anatomy in relation to taxonomy? Th...

Q. Anatomy in relation to taxonomy? The use of anatomical* characters in taxonomy began with the development of the microscope which provided the biologist a new tool to observ

Explain the bioavailability of vitamin d, Explain the Bioavailability of Vi...

Explain the Bioavailability of Vitamin D? The nutritional availability of vitamin D is less significant because it can be endogenously produced and retained for long periods by

Genetics, What are the Elements of Heredity and variations?

What are the Elements of Heredity and variations?

Explain the following terms in detail - homology, Explain the following ter...

Explain the following terms in detail - Homology, Homologous ? Structures that have a similar evolutionary origin however different functions. The wing of a bat and a whale's fl

Agro industrial-calcium, Calcium   The calcium content in forages is affe...

Calcium   The calcium content in forages is affected by species, plant part (leaf versus stem), plant maturity, soil content of calcium and climate. Forages are usually a good so

What is the drug permeability across the cornea, What is the drug permeabil...

What is the drug permeability across the cornea? Drug permeability across the cornea depends onto: a. Lipid and water solubility of the drug b. Molecular size, weight and

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