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

Aujeszky''s disease, Aujeszky's disease This is primarily a disease of...

Aujeszky's disease This is primarily a disease of pigs, which serve as the principal reservoir host. The secondary hosts include cattle, horse, sheep, goat, dog and cat but hu

Principles of bcc, Principles of BCC · BCC should be integrated with p...

Principles of BCC · BCC should be integrated with program goals from the beginning. BCC is a necessary part of diabetes prevention, care and support programs, and providing li

What is oxytocin receptors, Which of the following serves as an actuating s...

Which of the following serves as an actuating signal, or as part of an actuating signal, in a positive feedback system? A. Blood plasma levels of PTH (Parathryroid Hormone).

Protozoa, advantages and disadvantages of protozoa

advantages and disadvantages of protozoa

Adaptation, Adaptation Closely related to irritability is the capacit...

Adaptation Closely related to irritability is the capacity of living things for adaptation. You might have noticed that whenever you go outside in the bright sun after having

Diet of a msud patient, The diet of a MSUD patient (child) should therefore...

The diet of a MSUD patient (child) should therefore involve: • Measured quantities of natural protein or leucine from foods. • A BCAA free protein, vitamin and mineral supp

Structures of a flowering plant, Which structures of a flowering plant give...

Which structures of a flowering plant give rise to (a) potatoes, (b) the fleshy scales of an onion?   (a) A potato is a tuber formed at the end of an underground stem (b) O

Eating foods with high sweetness, Why would a tongue not detect mild sweetn...

Why would a tongue not detect mild sweetness after eating foods with high sweetness? This happens due to of the "desensitization" of sensory receptors on the sensory cells of y

Explain iron balance and regulation of iron absorption, Explain Iron Balanc...

Explain Iron Balance and Regulation of Iron Absorption? The body has three unique mechanisms for maintaining iron balance. The first is the continuous reutilization of iron fro

Spinal cord sectioned at the cervical level, Q. How is it explained that a ...

Q. How is it explained that a person with the spinal cord sectioned at the cervical level is still able to perform the patellar reflex? The arch reflex depends only on the inte

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