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 the chemical carcinogens, Explain about the Chemical Carcinog...

Explain about the Chemical Carcinogens? Chemicals have been shown to be carcinogenic. Some are naturally occurring components of plants and microbial organisms. Some are synthe

Illustrate artificial active immunization, Q. What are artificial active im...

Q. What are artificial active immunization and natural active immunization? Natural active immunization is that in which a previous natural infection induces the primary immune

Zinc (zn) - micronutrients, Zinc (Zn) - Micronutrients In its function...

Zinc (Zn) - Micronutrients In its function in some enzyme systems, zn 2+ resembles Mn 2+ in that it brings about substrate binding and conformational changes in enzymes. A n

Domestic waste water management, All the water used in the home that goes i...

All the water used in the home that goes into the drain or into sewage collection system is called waste water. Domestic sewage is the waste water from kitchens, bathrooms etc. It

Fishes- regeneration in vertebrates, Fishes- Regeneration in Vertebrates ...

Fishes- Regeneration in Vertebrates Several different parts of the fish body will re-grow. Plucked scales are promptly replaced by new ones and amputated gill filaments can re

Methods by which diseases are transmitted, There are several methods by whi...

There are several methods by which a disease-causing organism can be transferred from the reservoir to the host organism. Direct contact : Disease - causing organism may be tr

Closed heart surgery, CLOSED HEART SURGERY :  Operative procedures on ...

CLOSED HEART SURGERY :  Operative procedures on the heart or major intra thoracic vessels done when the heart is beating and supporting effective circulation come under the ca

Phylum annelida are vascular beings, Q. What is signifying when it is said ...

Q. What is signifying when it is said that beings of the phylum Annelida are vascular beings? From which other phyla of the animal kingdom does this feature differentiate them?

Blood, what are the component of hemoglobin

what are the component of hemoglobin

Difference between carriers of hiv and aids patients, What is the differenc...

What is the difference between carriers of HIV and AIDS patients? A person can be a carrier of the HIV without necessarily being affected by the immunodeficiency syndrome at 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