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

What are the symptoms causes of fever, During a fever in a human, A. sh...

During a fever in a human, A. shivering can happen when the actual body temperature is higher than the set point for body temperature during the fever. B. the control system

What is the cardiovascular system, What is the cardiovascular system Th...

What is the cardiovascular system The cardiovascular system, nervous system, kidneys and special sensory organ, eyes is directly affected by diabetes and leads to fatal conditi

Define the factors that affect the rate of drying, Define the Factors that ...

Define the Factors that Affect the Rate of Drying? Factors that affect the rate of drying are as follow: 1) The fat content of the food-Higher fat contents generally result

How can triglycerides be decreased, Q. How can triglycerides be decreased? ...

Q. How can triglycerides be decreased? Triglycerides could be decreased by: - limiting foods high in fats - decreasing sugar and sugar containing foods (carbonated bevera

Explain adverse effects of efavirenz, Adverse effects of Efavirenz The ...

Adverse effects of Efavirenz The most common adverse effects have been rash, dizziness, headache, insomnia and inability to concentrate. Vivid dreams, nightmares and hallucinat

Explain the working of specific acquired immunity, Working of Specific Acqu...

Working of Specific Acquired Immunity Primary lymphoid organs, as you already know, are thymus and bone marrow. Secondary organs are lymph nodes, spleen and lymphoid tissue. Wh

What are risk factors for diseases, What are risk factors for diseases? ...

What are risk factors for diseases? Risk factors for a disease are everything that contributes to enhance the risk of the disease to appear. For instance, for most cardiovascul

Write short note on gluconeogenesis, Gluconeogenesis that is also called as...

Gluconeogenesis that is also called as GNG is a metabolic pathway which results in the generation of glucose from non-carbohydrate carbon substrates such as pyruvate, glycerol, lac

Enzymes, what is the composition of enzymes ?

what is the composition of enzymes ?

Hormones secreted by the thyroid gland, Q. What are the hormones secreted b...

Q. What are the hormones secreted by the thyroid gland? What are their functions? The thyroid secretes the triiodothyronine (T3), hormones thyroxine (T4) and calcitonin. T3

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