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

What is the gross primary production of an ecosystem, Q. What is the gross ...

Q. What is the gross primary production of an ecosystem? How does GPP relate to photosynthesis? The Gross primary production of a GPP or ecosystem is the quantity of organic ma

Dietary recommendations during diarrhoea, Q. Dietary Recommendations during...

Q. Dietary Recommendations during Diarrhoea? The diet should take into account the normal RDI and various adjustments made to the quantity and quality of the foods to be given.

Protozoa, locomotion in parameceum

locomotion in parameceum

How are antivenoms produced, Q. How are antivenoms produced? Why are antive...

Q. How are antivenoms produced? Why are antivenoms an example of passive immunization? Antivenoms are obtained by the following process: the venom (antigen) is inoculated into

Temporary partial disability - injury from an accident, Temporary Partial D...

Temporary Partial Disability - Injury from an Accident Such types of injuries which are easily recoverable and may not incapacitate the victim to perform duty apart from for

Types of respiratory organs, Types of Respiratory Organs Respiratory o...

Types of Respiratory Organs Respiratory organs may be of the following types: Those that have respiratory surface turned out forming an evagination. These are called gi

Caruncle - seed appendages, Caruncle - Seed Appendages This is a white...

Caruncle - Seed Appendages This is a white, collar-like structure borne on the micropylar end of the seed in many members of the Euphorbiaceae, such as castor, Ricinus communi

What is concepts of chromosome, Q. What is the relation between the concept...

Q. What is the relation between the concepts of chromosome and chromatin? Are heterochromatin and euchromatin part of chromosomes? Every filament of chromatin is a complete DNA

What are the cell movements, Q. What are the cell movements and how are the...

Q. What are the cell movements and how are these movements created? Cell movements are movements executed by cell structures, like the movements of flagella and cilia, the pseu

Cells are miniature chemical factory, Cells is a Miniature Chemical Factory...

Cells is a Miniature Chemical Factory Due  to its incessant metabolic processes, a living   cell earns the  attribute  of a  miniature chemical factory   metabolites and  free

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