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 are the major representatives of the pteridophytes, Q. What are the ma...

Q. What are the major representatives of the pteridophytes? Is this plant group phanerogamic or cryptogamic? The better known pteridophytes are the ferns and the maidenhairs, f

Biochemical production , Biochemical Production: Plants are the foundat...

Biochemical Production: Plants are the foundation of a large variety of biochemical which are metabolites of both secondary and primary metabolism. But secondary metabolites ar

What is embryonic origin of the nervous system in vertebrate, How does the ...

How does the embryo turn from gastrula into neurula? How is the neural tube formed? What is the embryonic origin of the nervous system in vertebrates? The neurula stage is divi

Explain femoral approach, Q. Explain Femoral Approach? This approach in...

Q. Explain Femoral Approach? This approach involves the insertion of a catheter over a guidewire i.e. inserted into a sheath in the right femoral artery. Systemic anticoagulati

Budding, What processes occur during the budding of yeast?

What processes occur during the budding of yeast?

Assessment of peripheral vascular perfusion (beside test), Assessment of Pe...

Assessment of Peripheral Vascular Perfusion (Beside Test) Burger's Postural Test Perform in daylight.  Place patient supine with both legs elevated and knees

Research, i want to online research biology projects

i want to online research biology projects

Heterotrophic nutrition, heterotrophic nutrition in any 5 type...

heterotrophic nutrition in any 5 types of organism

U, uses of conductometry in biological experiments

uses of conductometry in biological experiments

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