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

Is vacuoles easily found in fresh or in salt water, Are protozoans presenti...

Are protozoans presenting contractile, or pulsatile, vacuoles easily found in fresh or in salt water? Fresh water is the less concentrated of solutes than sea water and it (fre

Sericulture industry, in sericulture industry do which stages of silkworm w...

in sericulture industry do which stages of silkworm weaver buy? why do they do so?

Determine the factors that influence manganese absorption, Determine the Fa...

Determine the Factors that Influence manganese absorption? Let us now see which factors influence Mn absorption. Major factors which may influence the absorption of this min

Homologous proteins - amino acid sequence in fasta format, Please answer th...

Please answer the following question on Sequence Y: Protein databases 1. What sequence from which organism is this sequence most similar to? 2. Can you find any homo

Shapes of viruses, Shapes of viruses Viruses occur in a wide variety o...

Shapes of viruses Viruses occur in a wide variety of shapes. Some are spherical or polyhedral . Some are helical appearing cylindrical or rod-like and other are complex. Virus

Fructose-1, Fructose-1,6-bisphosphate  and Fructose-6-phosphate : The  conv...

Fructose-1,6-bisphosphate  and Fructose-6-phosphate : The  conversion of  fructose-1,6- bisphosphate  to fructose-6-phosphate is  catalysed by fluctose-1,6-bisphosphatase  which  i

Define criteria for assessment of pyridoxine status, Define Criteria for As...

Define Criteria for Assessment of Pyridoxine Status? Vitamin B 6 status is most appropriately evaluated by using a combination of indicators,  namely plasma PLP concentration,

Lipoproteins, LIPOPROTEINS They are complex biomolecules formed of -...

LIPOPROTEINS They are complex biomolecules formed of - T riglycerides, Phospholipids, Cholesterol and Proteins. Lipoproteins are of four types - Chylomicrons

Inter-relationships of classification, Inter-relationships of Classificatio...

Inter-relationships of Classification The aim of classification is to put together organisms on the basis of their similarities. But the question is what type of similarities?

What is the plant transpiration, What is the plant transpiration? What are ...

What is the plant transpiration? What are the two major types of plant transpiration process? Which of them is more important in volume? The Plant Transpiration is the loss of

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