Secondary egg envelopes, Biology

Assignment Help:

Secondary Egg Envelopes

These are secreted by oviducts and other accessory parts of genital organs while the egg is passing through them from ovary to the exterior.

a) In ovoviviparous sharks the egg is surrounded by a hard shell secreted by shell glands of the oviduct. The shell is drawn out as twisted horns which serve to entangle the egg among sea weeds.

b) In amphibians, the eggs are surrounded by a layer of jelly which protects the egg from adverse effects of sun rays, abrasion as well as from predators (because of its bad taste). The jelly absorbs water and swells.

 c) In birds, reptiles and monotremes, the secondary envelopes include the white of egg surrounding the yolky ovum, followed by inner and outer shell membranes (which are in close contact with one another) and the outermost calcareous shell which is 'porous. The shell is elastic and compressible when the egg is laid but it hardens on exposure to atmosphere.


Related Discussions:- Secondary egg envelopes

Dissociative (conversion) disorders, DISSOCIATIVE  (CONVERSION) DISORDERS: ...

DISSOCIATIVE  (CONVERSION) DISORDERS: There is normally a considerable degree of conscious control over the memories and sensations that can be selected for immediate attentio

Explain about the term - paediatric neuropsychologist, Explain about the te...

Explain about the term - paediatric neuropsychologist In the evaluation of infants and young children, all sources of reliable and valid data available to the paediatric neurop

What are the types of antigenic agents, Q. What are the types of antigenic ...

Q. What are the types of antigenic agents that may constitute vaccines? Vaccines can be constituted of dead agents of disease, of inactivated toxins, of inactivated agents of d

Explain the term- pupil, Explain the term- PUPIL Pupil is  the  apertu...

Explain the term- PUPIL Pupil is  the  aperture in  centre of  the  iris diaphragm that regulates entry  of  light into the eye. Colour of  pupil  is  said  to be  black. Actu

Intramuscular route of injection, Intramuscular Route of Injection P...

Intramuscular Route of Injection Purpose When rapid action is required.  When drug would prove irritating to the subcutaneous tissue.  Site selected must be whe

Describe cytokinesis in a plant cell, Describe cytokinesis in a plant cell....

Describe cytokinesis in a plant cell. Vesicles produced by the Golgi apparatus fuse at  the midline of the cell to form the cell plate, a  cell wall that elongates to divide th

Explain the pair of chromosomes and sex chromosomes, Explain the pair of c...

Explain the pair of chromosomes and Sex Chromosomes? Morgan also noticed that one pair of chromosomes is different in male and female flies, one of the male chromosomes being

Translation in eukaryotes, Transcription in eukaryotes, a much more complex...

Transcription in eukaryotes, a much more complex procedure than in prokaryotes. In the eukaryotes, translation and transcription take place in several cellular compartments that ar

What is the function of the feet in molluscs, Q. What is the function of th...

Q. What is the function of the feet in molluscs? How is the mollusc foot related to the name given to the classes of the phylum? The mollusc foot has the function of support, l

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