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

How can coacervates formed of phospholipids or polypeptides, How can coacer...

How can coacervates be formed of phospholipids or polypeptides? Phospholipids are amphipathic molecules, i.e., they present a polar portion and a nonpolar portion. In contact w

Cnidaria and platyhelminthes - larval forms, Cnidaria and Platyhelminthes -...

Cnidaria and Platyhelminthes - Larval forms Cnidaria The common larval stage that is found in cnidarians is the planula which forms following gastrulation. The planula is

Classification scheme of protozoa, Classification Scheme of Protozoa ...

Classification Scheme of Protozoa Phylum Myxozoa Parasites of lower vertebrates especially fish and invertebrates. Phylum Microspora Parasites of inv

Determine the blood plasma levels of oxytocin, Which of the following serve...

Which of the following serves as an actuating signal, or as part of an actuating signal, in a system with feedback? (Either positive feedback or negative feedback) A. Blood pla

Homework, #questiocan you help in a biology question?.

#questiocan you help in a biology question?.

Explain gelation - function of proteins, Explain Gelation - Function of pro...

Explain Gelation - Function of proteins Gelation  refers to the process where denatured molecules aggregate to form an ordered protein network. Proteins  can form a well-order

Chloroplasts, Chloroplasts are disk-like organelles with the double membra...

Chloroplasts are disk-like organelles with the double membrane found in the eukaryotic plant cells; contain thylakoids and are the site of photosynthesis. ATP is generated during

#title.germ cell development, Ask questionhow are germ cells immortal #Mini...

Ask questionhow are germ cells immortal #Minimum 100 words accepted#

Contagious bovine pleuropneumonia, C o n t a g i o u s bovine pleu...

C o n t a g i o u s bovine pleuropneumonia It is a disease of bovines characterized by high rise of body temperature and difficulty in respiration. E t iolo

What is the role of the nad molecule in glycolysis?, What is NAD? What is t...

What is NAD? What is the role of the NAD molecule in glycolysis? NAD (nicotinamide adenine dinucleotide) is a hydrogen acceptor essential as reductant (to receive hydrogen) in

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