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

Absorption of glucose, Normal 0 false false false EN-IN...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

Determine the seeds in the plant kingdom, What is the evolutionary importan...

What is the evolutionary importance of the emergence of seeds in the plant kingdom? The evolutionary significance of the seed is related to the plant capability of distant colo

Ribosomes, Ribosomes - It is also known as Protein factory, Engine ...

Ribosomes - It is also known as Protein factory, Engine of the cell. Ribosomes are smallest cell organelles (150 x 250 Å). Unit membrane less cell organelle. Ribo

What are the near point and the far point of the vision, Q. What are the ne...

Q. What are the near point and the far point of the vision? The near point is the closest distance between the eye and an object that makes possible the formed image to be focu

Stratification - aquatic ecosystems, Stratification - Aquatic ecosystems ...

Stratification - Aquatic ecosystems Aquatic ecosystems also exhibit marked stratification. In lake and ocean ecosystems light penetration, temperature and availability of oxyg

Pre-requisites of counselling, In diabetes mellitus counsellor help the dia...

In diabetes mellitus counsellor help the diabetic patient to cope up with the stress and take own decision for their treatment and life style changes. Decision making  capacity of

Extraction of the tooth, Extraction of the tooth -In nonstrategic impo...

Extraction of the tooth -In nonstrategic importance -Diseased maxillary second molars with no opposing tooth , or with an opposing tooth in class l or lll occlusion that ar

Define the needs for enteral feeding, Define the needs for Enteral Feeding?...

Define the needs for Enteral Feeding? For enteral feeding following need to be considered: - In preterm calorie density to be 0.8 Kcal/ml, - LBW formulas used: protein -

What are the types of proteins in metabolism of lens, What are the types of...

What are the types of proteins in metabolism of lens? Soluble Proteins Its synthesis takes place in the equatorial part on the surface of lens. a. Alpha crystallins

Would induction of CYP 2E1 raise your blood alcohol level?, If I take a dru...

If I take a drug that induced the synthesis of CYP 2E1 in my system, would that raise or lower my blood alcohol level after I drink a beer or wine (compared to if I hadn''t taken t

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