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 advantages of periodontal ligament, Explain periodontal ligament ...

Explain periodontal ligament The absence of the periodontal ligament and the presence of osseointegration instead of the gomphosis joint leads to the difference in movement un

Visceral larva migrans, Visceral larva migrans Visceral larva migrans,...

Visceral larva migrans Visceral larva migrans, also known as larval granulomatosis, is a clinical syndrome produced by the extra-intestinal migration of larval nematodes and i

Prophase, Prophase This is the first and longest phase of mitosis .At i...

Prophase This is the first and longest phase of mitosis .At its beginning  all  10 nm segments   of chromatids (= chromonemata)  of the  duplicated  chromatin fibres of interph

Solid fuels, Primary and secondary solid fuels are widely used in domestic ...

Primary and secondary solid fuels are widely used in domestic and industrial purpose. Wood and coal constitute the important primary solid fuels. The important secondary solid fuel

Analysis of amino acid sequence on particular peptide, Define Analysis of A...

Define Analysis of Amino Acid sequence on Particular Peptide? The analysis of the relative order or the sequence in which the ammo acids are arranged-along the length of the

What are x-linked traits, What are X-linked traits? The X-linked traits...

What are X-linked traits? The X-linked traits are the phenotypical traits conditioned by genes located in the nonhomologous (heterologous) portions of the X chromosome.

Define protein requirements for physical fitness, Define Protein Requiremen...

Define Protein Requirements for physical fitness? Proteins provide energy to the body. Since exercise may increase an athlete's need for protein, depending on the type and freq

Explain restrictive cardiomyopathy, Q. Explain Restrictive cardiomyopathy? ...

Q. Explain Restrictive cardiomyopathy? It is a systemic or idiopathic disorder of the myocardium with clinical and hemodynamic features of diastolic dysfunction, closely simula

Explain first stage of the embryonic development, Q. What is the cell divis...

Q. What is the cell division during the first stage of the embryonic development called? How is this stage characterized? The cell division in the first stage of the embryonic

Define about the carbohydrates, Define about the Carbohydrates? In the ...

Define about the Carbohydrates? In the previous unit, we came to know that availability of glucose is the major factor in exercise performance. Hence, carbohydrate manipulation

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