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 electro osmosis , What is Electro osmosis ? Electro osmosis :...

What is Electro osmosis ? Electro osmosis :  Electroosmosis is the movement of charged molecules along a charged surfaces in response to a voltage difference. For example, e

Diseases caused by viruses, Diseases Caused by Viruses In the early day...

Diseases Caused by Viruses In the early days of microbiology, the disease producing submicroscopic agents were termed as 'filterable viruses' because of their ability to pass t

Flow cytometry, Ask que1. Design a 4 colour Flow cytometry experiment with ...

Ask que1. Design a 4 colour Flow cytometry experiment with an aim to identify B220-, CD3+, CD4+ (DOUBLE POSITIVE) AND B220+, CD3-, CD4- (DOUBLE NEGATIVE) cells. Select from the fol

Define working of body surface in excretion of zinc in human, Define workin...

Define working of Body surface in excretion of zinc in human? Loss of zinc occurs due to the exfoliation of skin and sweating (0.7 -1.0 mg/day). Another route of zinc loss is h

What ions must a plant obtain from the soil, What ions must a plant obtain ...

What ions must a plant obtain from the soil in order to make (a) ATP, (b) chlorophyll?   (a) To create ATP (adenosine triphosphate) a plant requires a supply of phosphate io

Signify the term - pectoral girdle., Signify the term - Pectoral girdle. ...

Signify the term - Pectoral girdle. Bones in vertebrates that connect the appendages on the left and right side of the anterior appendicular skeleton to each other. Pectoral gi

Explain about enzymes, Explain about enzymes All enzymes are proteins. ...

Explain about enzymes All enzymes are proteins. Many enzyme  proteins lack catalytic activity in the absence of a non-protein component, called a 'co-factor'. In this case, the

Leucosolenia, characteristics of leucosolenia?

characteristics of leucosolenia?

Determine the blood plasma levels of glucagon, Determine the blood plasma l...

Determine the blood plasma levels of glucagon A. production in the liver increases in response to an increase in blood plasma levels of glucagon. B. is secreted by alpha-isl

Explain the probiotics in foods, Explain the Probiotics in Foods? Yoghu...

Explain the Probiotics in Foods? Yoghurts have been supplemented with probiotic strains of bifidobacteria and Lactobacilli. Milks fermented solely by intestinal isolates of lac

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