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

Explain national nutritional anaemia prophylaxis programme, Explain Nationa...

Explain National Nutritional Anaemia Prophylaxis Programme (NNAPP)? In past, both access to and intake of iron-folate tablets have been poor in children and therefore had a lit

What are the glucagon receptors in the plasma membranes, Which of the follo...

Which of the following serves as an effector, or as part of an effector, that functions in a negative feedback system? A. Glucagon Receptors in the plasma membranes of alpha-is

Correction of reversible causes, In the long term reversible causes of hear...

In the long term reversible causes of heart failure like valvular lesions, myocardial ischemia, uncontrolled hypertension, arrhythmias, alcohol, negative inotropic agents, intracar

What is the main risk factor for lung cancer, Q. What is the main risk fact...

Q. What is the main risk factor for lung cancer? The major risk factor for lung cancer is tobacco smoking. In The large number of cases of this kind of cancer is due to the inc

Introduction to biodiversity, Biological diversity is the new buzzword, the...

Biological diversity is the new buzzword, the magic door to international funding and global travelling. We share the earth with million of other living beings. Just as we humans m

Explain about the prebiotics, Explain about the Prebiotics? Ingredients...

Explain about the Prebiotics? Ingredients/compounds that have a beneficial effect on microflora in the large intestine of the host e.g. fibre, fructo oligosaccharides, lactulos

What is a phenotype, What is a phenotype? A phenotype is each observabl...

What is a phenotype? A phenotype is each observable characteristic of a living being conditioned by its genes. Some phenotypes may be changed by nongenetic factors (for instanc

Blood, what are the component of hemoglobin

what are the component of hemoglobin

Determine the food source for magnesium, Determine the food source for Magn...

Determine the food source for Magnesium? Magnesium is widely distributed in variety of foods and beverages. In plants it is associated with chlorophyll. Thus, green leafy veget

Chemicals responsible for imparting the sweetness, The chemicals responsibl...

The chemicals responsible for imparting the sweetness, classic salt taste and bitter and sour taste are summarized herewith.  A. Sweet Taste Sweetness is one of the most importa

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