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

Methods by which diseases are transmitted, There are several methods by whi...

There are several methods by which a disease-causing organism can be transferred from the reservoir to the host organism. Direct contact : Disease - causing organism may be tr

What are the stages into which photosynthesis is divided, What are the stag...

What are the stages into which photosynthesis is divided? Photosynthesis is separated into the photochemical stage, or light reactions, and the chemical stage. Photosynthesi

Explain benefits of protein, Explain benefits of Protein Protein: Once ...

Explain benefits of Protein Protein: Once the energy requirements have  been estimated, protein requirements can be addressed. The aim is to achieve nitrogen balance. There are

Solubility of gases in water, Solubility of Gases in water Most gases w...

Solubility of Gases in water Most gases which are important for biological processes dissolve readily and specially in water. The solubility of any gas in water generally var

Define short- lived climatic stressful conditions, How do organisms like:- ...

How do organisms like:- a) fungi, b) zooplanktons and c) bears overcome the temporary short- lived climatic stressful conditions? Define.

Define the different forms of protein energy malnutrition, Define the Diffe...

Define the Different Forms of Protein Energy Malnutrition? The term PEM is used to describe a wide range of clinical conditions ranging 'from the very clinically detectable flo

Reproduction, Which are the larval stages of Porifera?

Which are the larval stages of Porifera?

What are the healing events around implants, Healing Events around Implants...

Healing Events around Implants Healing of an implant is compared with the processes in normal bone healing or bone regeneration and with stable osteosynthesis.

Phylum platyhelminhes, what are the classification of phylum platyhelminthe...

what are the classification of phylum platyhelminthes?

Discuss in detail about the close head injuries, Discuss in detail about th...

Discuss in detail about the Close Head Injuries Closed-head injuries result from a blow to the head, which can subject the brain to a variety of mechanical forces: Damag

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