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

Define nutritional availability - microbial survival, Define Nutritional Av...

Define Nutritional Availability - Microbial Survival and Growth? Food borne microbes are chemotrophs. Generally the types of microorganisms present on a particular food are the

Define the process of small intestine during digestion, Q. What is the subs...

Q. What is the substance produced in the liver that acts in the small intestine during digestion? How does that substance act in the digestive process? Bile is an emulsifier li

What do you mean by echinodermata, Q. What do you mean by Echinodermata? ...

Q. What do you mean by Echinodermata? You will recall that Pliylum Echinodermata includes spiny skinned animals which are exclusively marine (Gr, echinus : spiny; derma: ski

Fats , FATS ( = True Fats, Triglycerides, Neutral Fats) They are es...

FATS ( = True Fats, Triglycerides, Neutral Fats) They are esters of fatty acids and 3-carbon trihydric alcohol glycerol (= glycerine). T rue fat is also called trig

Why photoperiodism affect the flowering of some plants, How does the photop...

How does the photoperiodism affect the flowering of some plants? Flowering is a typical and simple to observe instance of photoperiodism. Most flowering plants flower only duri

Genetics Problems, Andalusian chickens may be either black, white, or gray....

Andalusian chickens may be either black, white, or gray. The gene for black is not dominant over the gene for white, nor is the gene for white dominant over the gene for black. Whe

Agro industrial-nutritive value of crop residues, Nutritive value of crop r...

Nutritive value of crop residues Nutritive value is generally determined by feed composition, intake and utilization  efficiency of digested matter. Thus, the value of a feed

Lorica - body form protozoans, Lorica - body form Protozoans It is a c...

Lorica - body form Protozoans It is a covering which unlike the theca fits loosely around the organism. It is a cup, bell or vase-like structure with one opening through which

Name two food additives needed to keep food wholesome, a) Name two food ad...

a) Name two food additives needed to keep food wholesome, and say what they do. b) Name two food additives (or types of additive) which are not necessary for keeping fo

Explain ganongs potometer, For measuring the rate of transpiration of a twi...

For measuring the rate of transpiration of a twig using Ganong's potometer, learner A cuts the twig and fits it in the broad end of the water-filled potometer. Learner B cuts the t

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