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

Give some examples of cloning and molecular biology, Examples of cloning an...

Examples of cloning and molecular biology cloning may produce heterozygous individuals (as mother was heterozygous) and suggests a way to get pure breeding cats molecu

Explain the function of the umbilical cord, Q. What is the function of the ...

Q. What is the function of the umbilical cord? The umbilical cord is a set of blood vessels that connects the fetus with the placenta and in the fetus one extremity of the cord

Biostatistics for clinical and public health research, Disease Y Study: Le...

Disease Y Study: Let us consider the Disease Y study, a brief description of the study is as follows. A case-control study was conducted of 75 cases with a rare genetic disorder "

Define the functions of vitamin a, Define the Functions of Vitamin A? V...

Define the Functions of Vitamin A? Vitamin A (retinol) is an essential nutrient needed in small amounts by humans for the normal functioning of the visual system, growth and de

Closed type of circulatory systems, Closed Type of Circulatory Systems ...

Closed Type of Circulatory Systems Some non-chordates, like cephalopods (octopuses, squids), earthworms, polychactes and all vertebrates have a closed circulation along with b

Ultrasonic removal of gutta percha, Ultrasonic removal of Gutta percha: ...

Ultrasonic removal of Gutta percha: -the piezoelestic ultrasonic system. - As the instruments is energized; producing heat to themosoften gutta-percha. - Float gutta-perc

Can you describe about folic acid, Q. What is folic acid? Why is the anemia...

Q. What is folic acid? Why is the anemia caused by deficiency of folic acid known as megaloblastic anemia? The folic acid when ionized it is called folate is a coenzyme that pa

Explain the role in insulin formation, Explain the Role in Insulin Formatio...

Explain the Role in Insulin Formation? You are aware that insulin receptors are present in many cells with their concentration being highest in adipocytes (cells present in adi

Hormones secreted by parathyroid gland, Hormon e . The chief cells of the ...

Hormon e . The chief cells of the parathyroids secrete a hormone called parathyroid hormone (PTH) or parathormone or also called Collip's hormone after the name of its discove

Describe the phylum chordata in animal kingdom, Describe the Phylum Chordat...

Describe the Phylum Chordata in animal kingdom? This is the other group of animals along with the Echinodermata whose anus develops prior to the mouth's development in the embr

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