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 ecosystem if the decomposers were eliminated, What would happ...

What would happen to the energy flow through an ecosystem if the decomposers were eliminated?  Without decomposers, the nutrients kept in the bodies and wastes of other organis

What the henderson-hasselbalch equation expresses, The Henderson-Hasselbalc...

The Henderson-Hasselbalch equation expresses the pH of a solution as: Select one: a. The equilibrium constant of the acid and the dissociated form of the weak acid. b. The

Describe primitive anaerobic eukaryotic cells, Q. How can the hypothesis th...

Q. How can the hypothesis that asserts that chloroplasts as well as mitochondria were primitive prokaryotes that related in mutualism with primitive anaerobic eukaryotic cells be c

Chordata, Structure of plasmodium

Structure of plasmodium

Lateral roots - root apex, Lateral Roots - Root Apex Lateral roots no...

Lateral Roots - Root Apex Lateral roots normally arise at a definite distance behind the tip from areas close to or opposite the points of xylem star. So, a triarch root can

What is abscess and gingival biotype, What is Abscess and Gingival Biotype ...

What is Abscess and Gingival Biotype Abscess: Rule out any presence of Periapical or /and Periodontal abscess Gingival Biotype: Thickness of the gingival is an important

Explain about chlorophylls - natural pigments, Explain about Chlorophylls ...

Explain about Chlorophylls Chlorophylls are used as colourants in a range of foodstuffs and both natural chlorophyll (containing magnesium as the central metal ion) and 'coppe

Explain vitamin B complex, Vitamin B Complex The vitamin B complex comp...

Vitamin B Complex The vitamin B complex comprises the vitamins B 1 , B 2 , B 6 and B 12 as well as the vitamin B factors biotin, folic acid, nicotinic acid and its amide as w

Photometer-radiation instrument, Photometer Photometer (Figure shown be...

Photometer Photometer (Figure shown below) measures the intensity of light. The metallic plate A is a photocell which emits electrons from its surface when light of sufficient

Explain dietary diversification - iron deficiency anaemia, Explain the Diet...

Explain the Dietary diversification - Iron Deficiency Anaemia? It aims to ensure that deficient populations have access to foods rich in iron and also foods rich in vitamin C (

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