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

Determine the term memory - psychological tests, Determine the term Memory ...

Determine the term Memory - Psychological tests The acquisition, reaction, and retrieval of new information is a domain of much importance in infants and young children at risk

Difference between phanerogamic and cryptogamic plants, Q. What is the diff...

Q. What is the difference between phanerogamic and cryptogamic plants? Cryptogamic (hidden sex organs) plants are those that do not present seeds or flowers. They comprise the

Photophosphorylation, explain the role of cyclic photophosphorylation in p...

explain the role of cyclic photophosphorylation in photosynthesis

Round worm, parasitic adaptation of round worm

parasitic adaptation of round worm

Respiratory distress syndrome, Respiratory Distress Syndrome: Respirat...

Respiratory Distress Syndrome: Respiratory distress in a  newborn is  a challenging problem.  It  accounts for significant morbidity and mortality. It occurs  in  4 to 6 per c

Define prevention of idd - communication campaign, Define prevention of IDD...

Define prevention of IDD - Communication Campaign? A mass communication campaign is needed to create awareness in the community about the consequences of IDD and the benefits o

How to calculate hydrogen ion concentration, Q. How to calculate Hydrogen I...

Q. How to calculate Hydrogen Ion Concentration? Ans. The hydrogen ion concentration has a significant role to play in growth of bacteria as every microorganism has a minim

Mollusca, in molluscathe foot is used for (capturing locomotion or both

in molluscathe foot is used for (capturing locomotion or both

List the heterotrophic nutrition in plants, a) List the a variety of modes ...

a) List the a variety of modes of heterotrophic nutrition in plants. b) Define any two modes giving one example of each.

Neo-lamarckism, NEO-LAMARCKISM Modem modified form of Lamarck theory...

NEO-LAMARCKISM Modem modified form of Lamarck theory is regarded as Neo-Lamarckism. Mc Dougall (1938) found that time taken for training the mice was reducing gradually

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