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

Climax forest - xerarch, Climax Forest - Xerarch First, some xerophyti...

Climax Forest - Xerarch First, some xerophytic species of trees, establish in this area. They are sparsely distributed and are stunted because the conditions are still not ver

Define reaction of fehling soxhlet method, Define Reaction of Fehling Soxhl...

Define Reaction of Fehling Soxhlet method? The reducing sugars formed are acted upon by the alkali of Fehling's solution to form enediols. These enediols are very unstable and

What are the gynoecium and the androecium, Q. What are the gynoecium and th...

Q. What are the gynoecium and the androecium? What are the other structures of flowers? Androecium is set of male reproductive structures of flowers it comprehends the stamens

HEALTHY DIET, EXPLAIN THE CONSTITUENT OF FOOD GROUPS AND THEIR SOURCES

EXPLAIN THE CONSTITUENT OF FOOD GROUPS AND THEIR SOURCES

The initial velocity of an enzyme catalyzed reaction, The initial velocit...

The initial velocity of  an  enzyme catalyzed reaction The mathematical relationship between  the initial velocity of  an  enzyme catalyzed reaction, the concentration of the s

Sieve tubes, What are sieve tubes suited for translocation of food? a.bord...

What are sieve tubes suited for translocation of food? a.bordered pits b.no end walls c.bordered lumen and perforated cross walls D.no protoplasm

Is crossing over important diversity of biological evolution, Is crossing o...

Is crossing over important for the diversity of biological evolution? The Sexual reproduction and the recombination of linked genes (crossing over) are, along with mutations, t

Determine the initiation of muscle contraction, Describe the Capillarity Th...

Describe the Capillarity Theory in respect of ascent of water in plants. Name the tissue included. Determine the initiation of muscle contraction. What is the role of Sarcoplas

Venous drainage of the heart, The coronary sinus is the main vein of the he...

The coronary sinus is the main vein of the heart and is about 3 cm. long. It lies in the coronary sulcus at the posterior surface of  the heart in the posterior atrio-ventricular g

What are vectors of parasites, Q. What are vectors of parasites? The Ve...

Q. What are vectors of parasites? The Vectors of a parasite are organisms can transport the parasite during stages of its life cycle mediating the infection of other hosts. For

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