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

Food gathering and hunting , Food Gathering and Hunting : Food Gatherin...

Food Gathering and Hunting : Food Gathering and Hunting In order to live, man needed to eat and to protect himself from the weather and animals.  For both purposes he found it

Genetic abnormalities caused by recessive genes, What are some diseases or ...

What are some diseases or genetic abnormalities caused by recessive genes? Instance of recessive genetic diseases are: cystic fibrosis, phenylketonuria, albinism, galactosemia,

Which chemical substances produced by water photolysis, Q. What are the che...

Q. What are the chemical substances produced by water photolysis and what is the destination of each of those substances? Free electrons, molecular oxygen and hydrogen ions are

What does the formula dpd = sf - tp mean, What does the formula DPD = SF - ...

What does the formula DPD = SF - TP mean? DPD is the abbreviation of diffusion pressure shortage, SF (suction force) is the vacuolar osmotic pressure and TP is the turgor press

Define general protection in the laboratory, Define General protection in t...

Define General protection in the Laboratory? You are required to wear a laboratory coat at all times in the laboratory. It is sensible to buy one of good quality and to launder

What is galactosemia, Q. What is Galactosemia? Galactosemia is a geneti...

Q. What is Galactosemia? Galactosemia is a genetic disorder caused by deficient functioning of any of these three enzymes namely galactokinase, galactose -1 - phosphate uridyl

Define distribution of food products – public nutrition, Define Distributio...

Define Distribution of Food Products - Public Nutrition? We learnt earlier that we have buffer stocks of food grains in our country. These stocks do help to combat acute transi

How are nematodes characterized, Q. Nematode identity card. How are nematod...

Q. Nematode identity card. How are nematodes characterized according to examples of representing beings, type of symmetry basic morphology, , germ layers and coelom, digestive syst

Minerals requirements for ulcerative colitis, Q. Minerals requirements for ...

Q. Minerals requirements for ulcerative colitis? Minerals: Mineral losses may be marked and unless replaced may contribute to a fatal outcome. A patient with moderately advance

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