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

Explain about folic acid, Explain about Folic acid Folic acid occurs as...

Explain about Folic acid Folic acid occurs as a yellow or orange-yellow, microcrystalline powder, almost without odour and taste. Water content of folic acid is up to 8.5%. Fol

Comparison with amphibian gastrulation, Comparison with Amphibian Gastrulat...

Comparison with Amphibian Gastrulation On comparison of chick gastrulation along with amphibian gastrulation you will find many similarities along with significant difference

Define the functions of vitamin e, Define the Functions of Vitamin E? V...

Define the Functions of Vitamin E? Vitamin E is the major lipid-soluble antioxidant in the cell antioxidant defence system and is exclusively obtained from the diet. The main r

Unilateral incompatibility, Unilateral Incompatibility This relates to...

Unilateral Incompatibility This relates to incompatibility that operates in one direction. The most common way to ascertain unilateral incompatibility is to perform crosses be

Explain water and electrolyte imbalance during kwashiorkor, Explain Water a...

Explain Water and electrolyte imbalance during kwashiorkor? The total body water and especially the extracellular fluid volume are increased in all forms of PEM. At the same ti

Renal failure and transplantation, KIDNE Y (RENAL FAILURE) - RF - Part...

KIDNE Y (RENAL FAILURE) - RF - Partial or total inability of kidney to carry excretory functions is called RF. It leads to uremia (excess of urea in blood), salt-water imba

What is the utility of fungi for some industries, What is the utility of fu...

What is the utility of fungi for some industries? Fungi are industrially used in the production of fermented beverage, cheese, bread etc. Some fungi are very significant for th

Explain the fluoride toxicity, Explain the Fluoride Toxicity? Fluoride ...

Explain the Fluoride Toxicity? Fluoride is a cumulative toxin. Ingestion of fluoride 1.0-1.5 mg/L for several years may produce dental fluorosis, i.e. browning and pitting of t

Preserving foods, One of man's oldest methods of preserving foods is drying...

One of man's oldest methods of preserving foods is drying or desiccation. The preservation of foods by drying is a direct result of removal of moisture. Microorganisms need water

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