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

Strain of fusarium moniliforme, Q. Strain of Fusarium moniliforme? It w...

Q. Strain of Fusarium moniliforme? It was first obtained from a strain of Fusarium moniliforme isolated from southern leaf blight- damaged corn seed as a water soluble toxin.

How can the immune memory lead to the efficacy of vaccines, How can the imm...

How can the immune memory lead to the efficacy of vaccines and also produce allergies? Vaccines are controlled inoculations of fragments of infectious agents or of inactive inf

Define tubular-dorsal nervous system, Q. How can the tubular-dorsal nervous...

Q. How can the tubular-dorsal nervous system in chordates be compared to the nervous pattern present in invertebrates? In chordates the nervous system is dorsal and highly ceph

Conductometry, conductometry and its uses in biological experiments

conductometry and its uses in biological experiments

Biochemistry, tertiary structure of protein

tertiary structure of protein

What are the factors that for influencing photosynthesis, What are the fact...

What are the factors that for influencing photosynthesis also interfere with the gross primary productivity? Mostly water and light, but also mineral salts, temperature and car

Reproduction, Normal 0 false false false EN-IN X-NONE...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

What is the most likely source of error in the study, In a cohort study tha...

In a cohort study that found an association between alcohol consumption and bladder cancer, 20,000 middle-aged men were asked about their drinking habits and then tracked for five

Define methods for determining ph - nutritional biochemistry, Define Method...

Define Methods for determining pH? There are two general methods for determining pH of a solution. One is the colorimetric method and the other most common method is the use of

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