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 sources of dietary fibre in our diet, Q. What are the sources ...

Q. What are the sources of dietary fibre in our diet? The sources of dietary fibre include whole grain cereals, legumes, whole pulses, leafy vegetables, vegetables like peas,

Explain briefly pinocytosis , Unlike the phagocytosis, that is a regul...

Unlike the phagocytosis, that is a regulated form of endocytosis carried out by a small number of cell category, pinocytosis is a constitutive process which happens continuously in

Explain the infraorbital nerve and vessels, Infraorbital nerve and vessels ...

Infraorbital nerve and vessels The infraorbital nerve exits through the infraorbital foramen. This foramen and the neurovascular contents are within 5 to10mm of extremely resor

Osseointegration in immediate placement of implants, Q. Osseointegration In...

Q. Osseointegration In Immediate Placement Of Implants? In routine procedures, delayed placement of implants is done. However, immediate placement of implants into fresh extrac

Explain about mandible, Q. Explain about Mandible? In the mandible, att...

Q. Explain about Mandible? In the mandible, attached keratinized tissue normally atrophies with the underlying bone. As a result there is generally a relatively narrow band of

What are the bone cells, Bone Cells Bone cells may be divided into two ...

Bone Cells Bone cells may be divided into two broad classifications depending on whether they make bone or resorb it. Osteoblasts make bone, while Osteoclasts resorb or take aw

Stds, define stds give 5 examples of stds give signs, symptoms, treatment a...

define stds give 5 examples of stds give signs, symptoms, treatment and prevention of each example

What is a prion, Q. What is a prion? The prion is an infectious (transm...

Q. What is a prion? The prion is an infectious (transmissible) protein able to replicate by transforming other proteins into a copy of the prion. The mechanism of the copying i

Define mechanism for copper absorption, Define Mechanism for Copper Absorpt...

Define Mechanism for Copper Absorption? As in the case of other minerals, copper absorption appears to occur by two mechanisms: i) Saturable active mechanism, which operates

Define essential parts of photocolorimeter - monochromators, Define Essenti...

Define Essential Parts of Photocolorimeter - Monochromators? This is a means of selecting a sufficiently narrow waveband. Early colorimeters used glass filters that transmitted

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