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 the term active transport, Explain the term active transport? ...

Explain the term active transport? Active Transport :  At intervals, protein assemblies involved in selective, or active transport of materials are inserted into the cell mem

Can you illutrate autoimmune diseases, Q. What is the name given to conditi...

Q. What is the name given to conditions in which the own immune system of the individual is the agent of diseases? What are some examples of these conditions? Diseases caused b

Automated dna sequencing, Automated DNA sequencing is now common place whic...

Automated DNA sequencing is now common place which is based on the chain termination method but using a fluorescent dye attached to an oligonucleotide primer instead of using radio

Determine the cardio-vascular system, Determine the Cardio-vascular System ...

Determine the Cardio-vascular System Cardio-vascular system consists of a heart and blood vessels. The function of cardio- vascular system is to maintain blood supply to all t

Steroids, STEROID S - These are derived lipids. Cholesterol is m...

STEROID S - These are derived lipids. Cholesterol is must in formation of steroid hormones. In steroids cyclopentanoperhydrophenentherene nucleus ring present. S

Annuloplasty with a ring, Annuloplasty with a Ring :  The lings commo...

Annuloplasty with a Ring :  The lings commonly used are Carpentier- Edwards and Cosgrove's flexible half ring. The rings are C shaped and have incomplete circles to accommoda

Equipment of cardio pulmonary bypass , Equipment : To maintain effective c...

Equipment : To maintain effective circulation and carry out functions of the lungs during an open heart operation the equipment should have: 1) Blood Pump 2) Oxygenator 3

Medtronic-hall valve-types of valves, Medtronic-Hall Valve :  This is...

Medtronic-Hall Valve :  This is a low profile central tilting disc valve. The disc is made of pyrolitic carbon and housing is single piece of machined titanium. Introduced in

How is water importance to life, How is water's importance to life reflecte...

How is water's importance to life reflected in the normal range of internal pH values that living things are likely to have?

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