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

What is the function of the umbilical cord, What is the function of the umb...

What is the function of the umbilical cord? The umbilical cord haves blood vessels which convey blood among the fetus and the placenta.

Unitary explanation for protein synthesis, Q. Why is the concept of a singl...

Q. Why is the concept of a single gene as ultimateunit of inheritance inadequate to provide a unitary explanation for protein synthesis, recombination and mutation? Answer:

Pisces fish, description on characteristics of pisces fish

description on characteristics of pisces fish

Amphibians, Ask questionImagine you are studying a group of amphibian speci...

Ask questionImagine you are studying a group of amphibian species that vary in their habitats, some living in dense murky water, and others living in very clear ponds. What kind of

Chemistry of living matter, Chemistry of Living Matter All living things ...

Chemistry of Living Matter All living things including ourselves, are made of protoplasm. Protoplasm is essentiallya colloidal suspension of proteins in a w&ery solution. It is c

Oestrous cycle, OESTROU S CYCLE - Also known as heat period. Common in...

OESTROU S CYCLE - Also known as heat period. Common in rabbit, cat, dog, sheeps. In this period desire for copulation occur. Possibility of fertilization is 100%.

Excretory organs, Normal 0 false false false EN-IN X-...

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

Inhibition of microbes by weak acids, With the exception of those soft drin...

With the exception of those soft drinks that contain phosphoric acid, in most other acidic foods acidity is due to the presence of weak organic acids. These do not dissociate comp

Explain the mortality and survivorship curves, Explain the Mortality and Su...

Explain the Mortality and Survivorship Curves? Mortality : Just as a population has a birth rate, so does it have a death rate. A populations rate of death, or the number of

Sources of stem cells-pulp tissue revascularization, A) General:   u...

A) General:   umbilical cord  Placenta  Bone marrow  Ophthalmic cornea { conjectiva of the eye }  Kidney  Spleen  (B) Dental:  Dental pulp

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