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 choanoflagellate. explain in brief., What is Choanoflagellate? Expl...

What is Choanoflagellate? Explain in brief. The protozoans which resemble the choanocyte cells found in sponges. They have a collar of microvilli which surround a central flage

Explain an important strategy of group meetings, Explain An important strat...

Explain An important strategy of group meetings An important strategy could be to conduct small group meetings for behavioural change encouraging full participation. The group

Points, What is the classification of protozoa with examples

What is the classification of protozoa with examples

Cuticle, what does cuticle mean

what does cuticle mean

Define equilibrium conditions in multicomponent systems, Define Equilibrium...

Define Equilibrium Conditions in Multicomponent Systems? This chapter applies equilibrium theory to a variety of chemical systems of more than one component. Two different appr

Basic principles involved ark, Q. Basic principles involved ark? The ba...

Q. Basic principles involved ark? The basic principles involved ark: The individual must be treated as such and for that careful initial history - daily living situation, a

Biosecurity in poultry health management, B i osecurity in Poultry Health...

B i osecurity in Poultry Health Management Biosecurity includes all the measures that are taken to prevent infection to individual, material and environment from the pathogen

Define the poverty and hunger as a causes of malnutrition, Define the Pover...

Define the Poverty and hunger - mutually causes, devastating effects? Measures of food deprivation, nutrition and poverty are strongly correlated. Countries with a high prevale

Nucleic acids, Why is the number of bonds important in nucleic acids

Why is the number of bonds important in nucleic acids

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