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

Preparation of dilutions - standard or total plate counts, Define Preparati...

Define Preparation of Dilutions - Standard or Total Plate Counts? 1. Serial dilution of homogenized sample in an appropriate diluent. Preparation of dilutions - Decimal dilu

Action of antibodies against virus and against bacteria, Q. How different a...

Q. How different are the actions of antibodies against virus and against bacteria? Why is the cellular immune response activated in case of chronic viral infection? The antibod

Plants, why roots grow downword

why roots grow downword

Acid hydrolysis of non-reducing sugar, Q. Acid Hydrolysis of Non-Reducing S...

Q. Acid Hydrolysis of Non-Reducing Sugar? It involves the acid hydrolysis of non-reducing sugars to reducing sugars. It is also known as the process of inversion. Acid hydrolys

Explain indications of root-end filling (ref) - retrofilling, Explain Indic...

Explain Indications of Root-End Filling (REF) Retrofilling a. Persistent periapical pathosis resulting from an inadequate apical seal that cannot be corrected nonsurgically,

Differentiation - morphogenesis and tissue organisation, Differentiation - ...

Differentiation - Morphogenesis and Tissue Organisation It should be clear to you that a single cell, the fertilized egg, gives rise to various structures that we mentioned. S

What is the nature of the stimulus received, What is the nature of the stim...

What is the nature of the stimulus received and transmitted by the neurons? Neurons receive and transmit chemical stimuli by neurotransmitters released in the synapses. Along

Horse diseases-japanese encephalitis, Japanese encephalitis The Japane...

Japanese encephalitis The Japanese encephalitis is a mosquito-born flavivirus infection that causes encephalitis in human and equines and abortion in pigs, caused by Japanese

Why tpp and ttp are vital for the nerves and cardiac tissues, Why TPP and T...

Why TPP and TTP are vital for the nerves and cardiac tissues? TPP and TTP are interconvertible and arc involved in carbohydrate metabolism. As discussed above, when there is in

Loop of henle, Normal 0 false false false EN-IN X-NON...

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

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