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

Genetic diversity of population, Genetic Diversity of Population The b...

Genetic Diversity of Population The biological diversity of animals, plants, and microorganisms is of fundamental importance to human survival. The term "gene resources" may b

What are colonies and societies, Q. What are colonies and societies? Th...

Q. What are colonies and societies? The Colonies are functional integrated aggregates formed by individuals of the similar species. The Colonies are often confused with a singl

Enlist the modalities available for hand wash, Q. Enlist the modalities ava...

Q. Enlist the modalities available for hand wash? Modalities available for hand wishing are a) 2-4% Chlorhexidine b) 0.3-1 %Triclosan c) 0.6% Parachlorometaxylenol (PC

What is the virus that causes flu, Q. What is the virus that causes flu? Wh...

Q. What is the virus that causes flu? Why doesn't the body produce permanent immunity against that virus? How does the vaccine against flu work? Flu is a disease caused through

What is the connection between tissue fluid and plasma, What is the connect...

What is the connection between tissue fluid, plasma and lymph? Tissue fluid is plasma (minus its proteins) which has leaked out of the capillaries. Lymph is tissue fluid which

Duodenum participating in extracellular digestion, Q. Besides the liver whi...

Q. Besides the liver which is the other adnexal gland of the digestive system that releases substances in the duodenum participating in extracellular digestion? The other adnex

Etiology, Etiology -Although this approach less desirable, it is useful...

Etiology -Although this approach less desirable, it is useful, short-term option if the etiology of the condition remains unknown. - The patient must inform about what will

Kingdom animalia, critera for the animal classification

critera for the animal classification

Impact of technological change on the cost of health service, Impact of Tec...

Impact of Technological Change on the Cost of Health Service Technological developments entail improvement in production/service frontiers either by providing cost benefit adv

Determine regulation of ph of body fluids, Blood functions to maintain home...

Blood functions to maintain homeostasis in the human body through all but which of the following: Answer moving carbon dioxide away from cells following completion of aerobic metab

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