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

Define the role of american dietetic association, Role of The American Diet...

Role of The American Dietetic Association The American Dietetic Association (ADA) remarked on the role of the dietitian in feeding dilemmas as:  the dietitian,  like other heal

Determine about the parameters of fitness, Determine about the Parameters o...

Determine about the Parameters of Fitness? There are five basic components of physical fitness, which involve heart, lungs, strength, endurance and flexibility. To improve the

Define the term - cholera, Define the term - Cholera Cholera is caused...

Define the term - Cholera Cholera is caused by the gram negative,  V. cholerae, which is acquired by ingesting food or water contaminated  by faecal material from patients or

What is the binding between two amino acids called, What is the binding bet...

What is the binding between two amino acids called? The chemical bond among two amino acids is called a peptide bond. Protein Structure Review - Image Diversity: peptide bo

Zoology, explain in detail various types of epithelial tissue

explain in detail various types of epithelial tissue

Define iron status of the individual, Define Iron Status of the Individual ...

Define Iron Status of the Individual Lastly, iron status of the individual is a floury determinant of how much iron is absorbed. On a mixed diet with some haem iron, the overal

What is the objectives of neuropsychological assessment, What is the Object...

What is the Objectives of Neuropsychological assessment?   Define and describe neuropsychological assessment; Elucidate the neuropsychological methodology for assessing i

Saliva spreading - temperature relations in animals, Normal 0 f...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

Oxygen affecting the growth of microorganism, oxygen affecting the growth o...

oxygen affecting the growth of microorganism? The presence of oxygen in the atmosphere is required for the survival of human beings. Contrary to this, you would realize that th

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