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 iodophors, In these disinfectants, iodine is incorporated along wi...

In these disinfectants, iodine is incorporated along with a detergent. They are not as effective as hypochlorites against bacterial spore but also get inactivated in the pres

Define the translocation of food through sieve tubes, Arrange the following...

Arrange the following processes sequentially to define the translocation of food through sieve tubes.   i. Unloading of sugar in sink cells (or cells of root).  ii. Uptak

Explain functional properties of gellan gums, Explain functional properties...

Explain functional properties of gellan gums One of the most important features of gellan gums is its versatile texture which is defined in terms of hardness (measure of ruptur

Explain pedicellaria in brief, Explain Pedicellaria in brief? Defensive...

Explain Pedicellaria in brief? Defensive pincerlike structures found on the surface of echinoderms. They are capable of responding to external stimuli independently from the ma

What is the uses of pet scans- brain function, What is the uses of PET scan...

What is the uses of PET scans- Brain function PET scans provide colour-coded images of person's brain as they undertake different sorts of task, such as reading words, solving

Crayfish, the appendages of arthropods; a. may serve as walking legs, b. ma...

the appendages of arthropods; a. may serve as walking legs, b. may be modified into atennae, c. may be modified into large pincers, or d. all of the above

How do contraceptive pills generally work, Q. How do contraceptive pills ge...

Q. How do contraceptive pills generally work? Contraceptive pills generally contain the hormones progesterone and estrogen. If taken daily from the 4th day after menses the abn

Metamorphosis, What type of metamorphosis do spongs go through is it reteog...

What type of metamorphosis do spongs go through is it reteogressive?

Improvement of cereal proteins - mutual supplementation, Define Improvement...

Define Improvement of cereal proteins - Mutual supplementation? Improvement of cereal proteins: Cereals, in general, are limiting in lysine and threonine while legumes, milk, m

Illustrate about insulin devices - insulin pen, Insulin Devices - Insulin P...

Insulin Devices - Insulin Pen Insulin pen is an insulin injection system. A pen consists of disposable needle, a vial of insulin and a pen. There are two pen systems replac

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