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

Tricuspid excision-types of surgery, Tricuspid Excision :  For tricus...

Tricuspid Excision :  For tricuspid valve endocarditis with vegetations in drug users, valve excision is done by removing three cusps and chordae and papillary muscles. Later

What kind of exoskeleton do some molluscs present, Q. What kind of exoskele...

Q. What kind of exoskeleton do some molluscs present? Some molluscs, like gastropods and bivalves secrete an external calcareous carapace (the shell). Calcium carbonate is a fo

The smooth er and rough er are similar functions, What functions of the smo...

What functions of the smooth ER and rough ER are similar?

Phototropic curvature is the result of uneven distribution, Phototropic cur...

Phototropic curvature is the result of uneven distribution of : 1. Gibberellin 2. Phytochrome 3. Cytokinins 4. Auxin Auxin

What is bone modeling, Bone Modeling It is a surface-specific activity ...

Bone Modeling It is a surface-specific activity (apposition or resorption) that produces a net change in the size and/or shape of a bone after initial bone formation in the emb

Determine the exercises require to do diabetic patient, Determine the Exerc...

Determine the Exercises require to do diabetic patient Exercises are any bodily activity that enhances or maintain physical fitness and overall health. It is performed for stre

Define the structure of hemicellulose, Structure of Hemicellulose When ...

Structure of Hemicellulose When compared with cellulose, it has lower degree of polymerization, more readily soluble in acid and alkali and non-fibrous. On hydrolysis, it predo

Osmotic function - essential elements, Osmotic Function - Essential Element...

Osmotic Function - Essential Elements Plant cells generally contain mineral ions 10 to 1000 times higher in concentration than the surrounding soil. That is why water enters t

Degrading monoglyceride, Degrade a monoglyceride that has an 18-carbon fatt...

Degrade a monoglyceride that has an 18-carbon fatty acid attached to it by Ester bonds. You will have to degrade the glycerol component followed by the fatty acid in presence of O2

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