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

How to load glycogen, How to load glycogen? Over the past fifty years, ...

How to load glycogen? Over the past fifty years, the biggest breakthrough was the discovery of how to load glycogen and sophistication in the methods of glycogen loading. Nitro

A decrease in blood plasma levels of parathyroid hormone, A decrease in blo...

A decrease in blood plasma levels of parathyroid hormone A. occurs in response to an increase in the levels of calcium ions in blood plasma. B. leads to an increase in the a

Animal Cells, what are the functions of cytoplasm ?

what are the functions of cytoplasm ?

What are the structures that form the external ear, Q. What are the structu...

Q. What are the structures that form the external ear? What is its function? The internal ear comprises the auricle or pinna and the auditory canal its function is to conduct t

Bovine viral diarrhoea, B o v i ne viral diarrhoea Bovine viral dia...

B o v i ne viral diarrhoea Bovine viral diarrhoea (BVD) and mucosal disease (MD) are clinically dissimilar disease syndrome yet have a common viral etiology. The acute dise

Cytokinesis, Cytokinesis It is defined  as the division or cleavage  of...

Cytokinesis It is defined  as the division or cleavage  of cytoplasmic  part   of the cells  into  two  daughter  cells. It is first  indicated   during  late  anaphase  by app

Nursing assessment - anomalies of stomach and oesophagus, Nursing Assessmen...

Nursing Assessment  These children present with excessive salivation and droofing of saliva from the mouth, coughing, gagging, even choking and cyanosis at the lime of first f

Name the groups into which flowering plants are divided, What are the two m...

What are the two main groups into which flowering plants are divided? Angiosperm plants are separated into a) Monocotyledonous (monocots) and b) Dicotyledonous (dicots

Human gene responsible for a form of muscular dystrophy, Graduate student D...

Graduate student Dee Innay works in a human genome lab, whose goal is to identify the human gene responsible for a form of muscular dystrophy (MD).  Dee has mapped the MD gene to a

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