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

Show the energy pyramids, Q. Can the amount of available energy in a given ...

Q. Can the amount of available energy in a given trophic level be larger than the available energy in inferior trophic levels? What does that condition means to the conformation of

The human impact on the environment, put the following events in the most p...

put the following events in the most probable order. A. Dead algae decomposed by bacteria B.excess nitrate and phosphate discharge into rivers C. Fish die of suffocation D.bacteria

Exchange of cells between the mother and the fetus, Q. Is there an exchange...

Q. Is there an exchange of cells between the mother and the fetus through the placenta? Under usual conditions there is no passage of cells across the placenta during gestation

Explain holding method of pasteurization, Explain holding method of pasteur...

Explain holding method of pasteurization In the holding method of pasteurization (62 o C for 30 minutes) or the high-temperature short-time (HTST), 71 o C for 15 minutes method

Which is the first heart chamber into which blood en, Which is the first (h...

Which is the first (human) heart chamber into which blood enters? Where does the blood go after passing that chamber? What is the name of the valve that separates the compartments?

How is excretion done in amphibians, Q. How is excretion done in amphibians...

Q. How is excretion done in amphibians? Adult amphibians have kidneys that filter blood. Nitrogen waste is excreted as urea so amphibians are ureotelic beings. The aquatic, lar

Veterinary medicine, Veterinary medicine Veterinary medicine is a branc...

Veterinary medicine Veterinary medicine is a branch of science that deals with diagnosis, treatment and control of diseases in animals such as livestock, domesticated animals,

Systolic versus diastolic failure, Systolic heart failure is a classic hear...

Systolic heart failure is a classic heart failure where the inotropic (contractile) state is impaired and the expulsion of blood is not adequate. So the main manifestations of syst

Explain about the primary protein derivatives, Explain about the primary pr...

Explain about the primary protein derivatives? a) Proteins: These are the insoluble products which result from the incipient action of very dilute acids or enzymes. e.g. casein

Ganong''s potometer, What happens to the movement of the air bubble if the ...

What happens to the movement of the air bubble if the apparatus is kept in i. In the dark ii. In sunlight iii.In front of a fan

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