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

Explain the clinical features of ps and vsd, Explain the Clinical Features ...

Explain the Clinical Features of PS and VSD ? Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

Differentiate between sterilization and disinfection, Q. Differentiate betw...

Q. Differentiate between sterilization and disinfection? Sterilization is defined as freeing the object or substance from all life of any kind. It is the process by which an ar

Theory of natural selection or darwinism, THEORY OF NATURAL SELECTION OR DA...

THEORY OF NATURAL SELECTION OR DARWINISM Theory of CharIes Darwin (1809 - 1882) about evolution marks the beginning of an era in understanding of evolution. At the age

Explain oleic - linoleic fats, Oleic - Linoleic Fats Fats in this grou...

Oleic - Linoleic Fats Fats in this group are the most abundant. The oils are all of vegetable origin and contain large amounts of oleic and linoleic acids, and less than 20%

Define photoorganoheterotrophs and chemoorganoheterotrophs, Photoorganohete...

Photoorganoheterotrophs and Chemoorganoheterotrophs - Nutritional Types (1) Photoorganoheterotrophs - These microorganisms use light as a source of energy and organic compound

Viruses, Viruses Viruses are sub cellular, ultramicroscopic infectious...

Viruses Viruses are sub cellular, ultramicroscopic infectious agents of 20 nm-300 nm size range Many of them cause diseases like polio, dengue, small pox, measles, rabies, com

Messenger rna (mrna), Messenger RNA (mRNA) are the proteins are not synthe...

Messenger RNA (mRNA) are the proteins are not synthesized directly from the genomic DNA. Insteadof that an RNA template (a precursor mRNA) is constructed from the sequence of gene

Principles of binomial nomenclature, Q. Principles of Binomial Nomenclature...

Q. Principles of Binomial Nomenclature? There are certain, basic principles of binomial nomenclature which are as follows: i) Different nomenclatural systems are independent

Explain cartilaginous and the osseous tissue, Which type of tissue are the ...

Which type of tissue are the cartilaginous and the osseous tissue? The cartilaginous and the osseous tissues are considered connective tissues as they are tissues in which the

What are the parathyroids, What are the parathyroids? Where are they locate...

What are the parathyroids? Where are they located and what are the hormones secreted by these glands? The parathyroids are four small glands embedded two in every posterior fac

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