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

Digestive System, When a piece of thread is tied tightly around an animal p...

When a piece of thread is tied tightly around an animal pancreatic duct the animal experiences difficult in digestion but does not suffer from diabetes mellitus.Explain why?

INVERTEBRATES - STRUCTURE & FUNCTION, 1. Write general characters of phylum...

1. Write general characters of phylum mollusca and classify it upto classes, giving at least two examples of each class.

How to prepare a key, Q. How to Prepare a Key? Let us prepare a key by ...

Q. How to Prepare a Key? Let us prepare a key by making a choice of. characters, listing significant and insignificant characters, tabulating these characters and forming dicho

Explain the concept of dressing, Explain the concpet of Dressing Dressi...

Explain the concpet of Dressing Dressing: Means medicine wound covering; a bandage or other sterile covering is put on a wound to protect it from infection or further damage.

Explain about the dehydration or drying, Explain about the Dehydration or D...

Explain about the Dehydration or Drying? The technique of drying is the oldest method of food preservation practiced by mankind. The removal of moisture, which is actually dehy

Cell theory, CEL L THEORY Proposed by Mathias Jacob Schleiden, 1838 (J...

CEL L THEORY Proposed by Mathias Jacob Schleiden, 1838 (Jerman Botanist), Theodore Schwann, 1839 (Jerman Zoologist) It consists of 5 fundamental facts - (i) Body of livi

How is the large size of some cephalopods, How is the large size of some ce...

How is the large size of some cephalopods related to the type of circulatory system they present? In cephalopods the circulatory system is closed and this gives more speed and

What are fitness tests, What are Fitness Tests? Testing is an important...

What are Fitness Tests? Testing is an important evaluation tool for the sports performer as it gives them an insight into their current physical condition and the effectiveness

Detailed explanation of effects of air pollution, On living organism  ...

On living organism           Air pollution causes following effects on living organism: (a)   Effects on humans: 1.      Carbon monoxide reduces the oxygen carrying cap

Effects on aquatic organisms - water pollution, Effects on Aquatic Organism...

Effects on Aquatic Organisms - Water Pollution Toxic water pollutants such as metals, pesticides, insecticides and chemicals affect aquatic species directly whereas the non-t

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