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

To show that growing seeds take in oxygen, To show that growing seeds take ...

To show that growing seeds take in oxygen Cork up one end of a tube, having first placed inside some damp cotton wool and some mustard seeds. Immerse the open end in dilute ca

Mutualist exploration of cellulose digestion, Q. What is meant by "mutualis...

Q. What is meant by "mutualist exploration of cellulose digestion", a phenomenon that occurs in some mammals and insects? Herbivorous animals eat great amounts of cellulose a s

Active transport, Active transport is the transport of the molecules again...

Active transport is the transport of the molecules against the concentration gradient (from area of low concentration to area of high concentration) with the help of proteins in t

Protection against insect bites, Protection Against Insect Bites To mi...

Protection Against Insect Bites To minimize insect bites, travellers should wear light-colored, long-sleeved shirts, pants and socks. The most effective topical insect repelle

Explain the role of bones in human biology, Explain the role of Bones in hu...

Explain the role of Bones in human biology? Bone is covered by a tough outer membrane called the periosteum. The periosteum contains systems of capillaries that supply the bone

What are the destinations of those oxygen atoms, Photosynthesis is the most...

Photosynthesis is the most significant producer of molecular oxygen (O2) on our planet. From which molecule do oxygen atoms liberated by photosynthesis come? From which other molec

Arboriculture, Arboriculture : It deals with the cultivation of ornamental ...

Arboriculture : It deals with the cultivation of ornamental plants. Arboriculture is the cultivation, management or study of individual shrubs, trees, vines, or other perennial woo

Lymph, Why lymph is also called middle man of body

Why lymph is also called middle man of body

Observation of hemichordata, Q. Observation of Hemichordata ? • identif...

Q. Observation of Hemichordata ? • identify Balanoglossus as a hemicliordate and give its scientific and common name. • classify Balanogiossus LIP to the level of order.

Define some detrimental effects of fungi, Define some Detrimental Effects o...

Define some Detrimental Effects of Fungi? These cause diseases of animals and humans. These either cause superficial mycoses (infection of skin, hair and nails) or systemic

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