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 environmental factors influencing food production, Explain Environm...

Explain Environmental Factors influencing food production? You probably know that no agricultural region has a constant climate throughout the year. This is true even in the tr

Illustrate bite-wing radiographs, Q. Illustrate Bite-wing radiographs? ...

Q. Illustrate Bite-wing radiographs? The short and long-term evaluation of crestal bone loss around implants is best evaluated with intraoral radiographs. Threaded implants mak

Describe the relation between nutritional and infections, Nutritional and ...

Nutritional and Infections The interaction between nutrition and  infection  is  synergistic -  that is  nutritional deficiency lowers resistance  to infection and infection ag

Rinderpest, R in d e rp es t It is also known as cattle plague re...

R in d e rp es t It is also known as cattle plague resulting in high fever, diarrhoea and high mortality rates. In year 2006, OIE has declared that India is free from rin

What will be the final volume, Suppose a sample of 200 microliters of blood...

Suppose a sample of 200 microliters of blood needs to be diluted 1/50. How much diluents should be added and what will be the final volume? Show all steps.

Draw the relationship between jp and v, Given the cell described in Figure ...

Given the cell described in Figure 7.7 with a=100mM, Pk=1.0, and PNa=0.04, at steady state, plot the relationship between Jp and V.

Homo habilis, Two important human fossils that throw much light on the huma...

Two important human fossils that throw much light on the human ancestory were discovered in .Olduvai beds in Africa and in central Java respectively. Although the development of bi

Explain pollination and its types, Q. What is the pollination? What are the...

Q. What is the pollination? What are the major forms of pollination? The procedure in which pollen grains (the male gametophytes of phanerogamic plants) reach the female gameto

Aortic and pulmonary orifices, These circular orifices are located at the u...

These circular orifices are located at the upper ends of the outflow parts of the left and right ventricles respectively. The pulmonary orifice which is 3 cms, is 0.5 cm larger tha

Explain protease inhibitors, Protease inhibitors (PIs) Protease inhibi...

Protease inhibitors (PIs) Protease inhibitors prevent cleavage of protein precursors essential for HIV maturation, infection of new cells and viral replication. Use of a prote

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