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 the difference between disaccharides, Q. What is the difference bet...

Q. What is the difference between disaccharides and monosaccharides? What are some examples of monosaccharides and of disaccharides that form them? Monosaccharides are simple m

Obturator - ovule, Obturator - Ovule An obturator is an outgrowth of t...

Obturator - Ovule An obturator is an outgrowth of the placenta or funicle or integument or style near the micropyle. It is presumed to guide the pollen tube to the micropyle.

What is inharmonious ecological interaction, Q. What is inharmonious ecolog...

Q. What is inharmonious ecological interaction? The Inharmonious or negative ecological interaction is that in which at least one of the participating beings is harmed.

Why do vestigial structures persist in modern organisms, Why do vestigial s...

Why do vestigial structures persist in modern organisms? Explain the evidence that indicates that species evolve over time. The environment will not select for or against

Explain the procedure of taking blood pressure, Explain the Procedure of Ta...

Explain the Procedure of Taking Blood Pressure - Explain the procedure to the patient. In case patient is coming for first time to check the blood pressure explain to the patie

Cerebral palsy, Cerebral Palsy Cerebral palsy is a non-progressive neu...

Cerebral Palsy Cerebral palsy is a non-progressive neuromuscular disorder characterised by disorder of strength, muscle control, posture or movement due to brain injury, befor

PHYLUM ANNELIDA, GERENAL CHARACTERICS OF PHYLUM ANNELIDA

GERENAL CHARACTERICS OF PHYLUM ANNELIDA

Essentiality of phosphorus for growth of microorganism, Define Essentiality...

Define Essentiality of Phosphorus for Growth of Micro-Organism Phosphorus is used in the form of phosphate salt by microorganisms. It is involved in formation of nucleic acids,

What are the three major types of passive transport, Q. What are the three ...

Q. What are the three major types of passive transport? The three main types of passive transport are simple osmosis, diffusion and facilitated diffusion.

Infective endocarditis, Infective Endocarditis It is an infection of...

Infective Endocarditis It is an infection of the endocardial surface with micro organisms present in the lesion. The endocardium is contagions with the valves of the heart.

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