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

Technique of assessment of growth and development, TECHNIQUE OF ASSESSMENT ...

TECHNIQUE OF ASSESSMENT OF GROWTH AND DEVELOPMENT Measurement of physical growth in children is a key element in evaluation of the health status of children. Physical grow

Explain the health economics, Explain the Health Economics? Health econ...

Explain the Health Economics? Health economics concentrates on application of the principles and rules of economics in the sphere of health. In broad terms, it includes analysi

Inadequate dietary intake - cause of anaemia is dietary, Define Inadequate ...

Define Inadequate Dietary Intake - cause of anaemia is dietary? The commonest cause of anaemia is dietary inadequacy of iron. The dietary intakes arc usually half of the recomm

Determine the categories of Taxonomic breakdown, For convenience, living th...

For convenience, living things are placed into different groups. Taxonomic breakdown of living things comprises the following categories: Family, Class, Genus, Phylum, Order, K

Specialized structures that help the adhesion between cells, Q. What are th...

Q. What are the specialized structures that help the adhesion between cells? The structures responsible for the union of the epithelial cells are called cell junctions. The mai

Dreams, what do our brain and heart do when we are asleep?

what do our brain and heart do when we are asleep?

Quality control of feedstuffs, Quality control of feedstuffs Quality co...

Quality control of feedstuffs Quality control is essential at all stages in the production of compound feed so that animals could get wholesome balanced and nutritious feed. Th

Insects - hormones in growth and reproduction, Insects - Hormones in Growth...

Insects - Hormones in Growth and Reproduction In insects hormones regulate moulting and metamorphosis. The larvae or nymphs which hatch out of the eggs undergo regular moultin

Define the role of riboflavin in drug and lipid metabolism, Define the role...

Define the role of riboflavin in Drug and lipid metabolism? Flavoproteins catalyze dehydrogenation reactions, as well as, hydroxylations, oxidative decarobxylations, deoxygenat

What are living and nonliving reservoirs, What are living and nonliving res...

What are living and nonliving reservoirs? Viruses are both living as well as non-living. They have reservoirs of genes. A one nucleotide is a unit of gene. Viral genes make use

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