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

Urgency, Overcoming these difficulties is urgent. New instrumentation and ...

Overcoming these difficulties is urgent. New instrumentation and measurement process, coupled with a developing computational infrastructure, give both a flood of data and the pro

#amphibia, amphibia class characteristics

amphibia class characteristics

New Technology, What is the best microscope to get a detailed view of the p...

What is the best microscope to get a detailed view of the parts inside of a preserved plant cell

Explain prodecures of antimicrobial prophylaxis, Antimicrobial prophylaxis ...

Antimicrobial prophylaxis Antimicrobial prophylaxis is generally not indicated for cardiac catheterization, varicose vein surgery, most dermatologic and plastic surgery, arteri

Type one diabetes mellitus, Q. Type one Diabetes Mellitus? Type 1 DM oc...

Q. Type one Diabetes Mellitus? Type 1 DM occurs in children and adolescents (6-14 yrs). In this disease, the body makes little or no insulin. Daily injections of insulin are ne

What are the features of retrograde peri-implantitis, The Features of Retro...

The Features of Retrograde Peri-Implantitis include: - Periapical Bone loss without gingival inflammation. - Microflora consisting mainly of streptococci and nonmotile organ

What is the likely function of the snf gene, In yeast, a new mutation calle...

In yeast, a new mutation called suc was recently discovered.  The suc mutant cannot use sucrose as a source of carbon, and will not grow if the culture medium contains only sucrose

Define intracellular cytoplasmic calcium concentration, How intracellular c...

How intracellular cytoplasmic calcium concentration is maintained? Intracellular cytoplasmic calcium concentration is maintained by the following mechanisms: a) Limited entr

Denaturizing be classified regarding its reversibility, How can denaturizin...

How can denaturizing be classified regarding its reversibility? Ans) Protein denaturizing can be a reversible or irreversible process, i.e., it can be possible or impossible to

How can triglycerides be decreased, Q. How can triglycerides be decreased? ...

Q. How can triglycerides be decreased? Triglycerides could be decreased by: - limiting foods high in fats - decreasing sugar and sugar containing foods (carbonated bevera

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