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

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.

Mitral valve repair-indications for surgery, Mitral Valve Repair :  When...

Mitral Valve Repair :  Whenever possible, the valve has to be repaired rather than replaced. Preoperative investigations and a TEE done on the operating table will help the surg

Pulmonary edema, Pulmonary edema occurs when movement of liquid from the bl...

Pulmonary edema occurs when movement of liquid from the blood to the interstitial space and/or into the alveoli exceeds the return of liquid to the blood and its drainage through t

In vivo imaging in psychiatry, In vivo imaging in psychiatry To illustr...

In vivo imaging in psychiatry To illustrate the ingenious applications to which in vivo imaging can be put, consider the use of PET in the study of hallucinations by Frith and

What is expression of the dominant phenotype, If we make a cross of two phe...

If we make a cross of two phenotypically WT zebrafish, and we get the following results, what can we say about the genotype of those two WT looking parents from the following resul

Protein case study, DK is a year old female who was born after a normal pre...

DK is a year old female who was born after a normal pregnancy and delivery.  At 17 months of age DK showed signs of speech delay, increased lethargy and vomiting up to four times p

Ant species in the two regions, Calculate a 95% confidence interval for the...

Calculate a 95% confidence interval for the difference among the average numbers of ant species in the two regions. Compare your results to SPSS output and interpret the confidence

Cystitis, C y s t i t i s It is the inflammation of urinary blad...

C y s t i t i s It is the inflammation of urinary bladder characterized by frequent painful urination and presence of blood and cells in urine. E t iology:

What are the basic constituents of the cell membrane, The cell membrane is ...

The cell membrane is produced of lipids, proteins and carbohydrates. The membrane lipids are phospholipids, a particular type of lipid to which one extremity a phosphate group i

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