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 the uses of isP in infant formulas, Explain the Uses of ISP in Infa...

Explain the Uses of ISP in Infant formulas Infant formulas  Infant formulas, where milk solids have been changed by soy products, are well established commercial products

What is ascaris and which disease caused by this worm, Q. What is ascaris? ...

Q. What is ascaris? What is the disease caused by this worm? Ascaris lumbricoides or Ascaris is an animal of the nematode phylum that is a roundworm. Ascaris causes ascariasis,

Homework, why do ecological models commonly have limited applications?

why do ecological models commonly have limited applications?

Tissue valves -surgical techniques, Tissue Valves :  Tissue valves mo...

Tissue Valves :  Tissue valves mounted on a frame with a sewing ring are inserted by the same technique as used in the case of prosthetic valves.

Algae, classificationof algae

classificationof algae

DNA, what is the genetic code of life

what is the genetic code of life

Human impact on environment, questions and answers on human impacts on envi...

questions and answers on human impacts on environment

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

Cardio pulmonary bypass , CARDIO PULMONARY BYPASS  :  Open-heart surgery i...

CARDIO PULMONARY BYPASS  :  Open-heart surgery is considered as one of the most significant advances in medicine of 20th century. Establishment of safe cardio pulmonary bypass (CP

Structure and function of lipoproteins, Triacylglycerols, cholesterol and p...

Triacylglycerols, cholesterol and phospholipids are associatively insoluble in aqueous solution. Thus, they are transported around the body in the blood as parts of lipoproteins.

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