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

What is ground meristem in primary growing shoot, What is Ground Meristem i...

What is Ground Meristem in primary growing shoot? The ground meristem produces new cells which ultimately develop into parenchyma cells. The central portion of the primary shoo

What is skeletal girdles? explain in brief., What is Skeletal girdles? Expl...

What is Skeletal girdles? Explain in brief. In vertebrates, bones which connect the appendages on the left and right side of appendicular skeleton to each other. Skeletal girdl

What do you understand by hypelglycemia, Q. What do you understand by Hypel...

Q. What do you understand by Hypelglycemia? Hypelglycemia (abnormally high blood sugar): Maintenance of blood glucose levels within or close to the normal range has been stress

Causes of cancer, Causes of Cancer Scientists have identified the cellu...

Causes of Cancer Scientists have identified the cellular genes that code for those proteins which jointly control and regulate cell growth and division. These  genes are of two

Carbohydrate required for underweight - nutritional care, Explain the Carbo...

Explain the Carbohydrate required for underweight - Nutritional Care? Liberal amounts of easy to digest carbohydrates should be included in the diet. The intake of dietary fibr

What is molting, What is Molting? Explain in brief. The periodic sheddi...

What is Molting? Explain in brief. The periodic shedding of outer body covering of an animal. The term is applied to a variety of things including: loss of the outer exoskeleto

What are the male pronucleus and the female pronucleus, Q. What are the mal...

Q. What are the male pronucleus and the female pronucleus? The female pronucleus is the proper haploid nucleus of the egg cell and Male pronucleus is the haploid nucleus of the

Emulsion products, E m u l s io n products Ground meat products s...

E m u l s io n products Ground meat products such as sausages, patties and luncheon meats are emulsion based products and their quality depends upon the ability of lean m

State the continuous sutures suturing technique, State the Continuous sutur...

State the Continuous sutures Suturing technique It can be used to attach 2 surgical flap edges or to secure multiple interproximal papillae of one flap independently of the oth

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