Extra-embryonic membranes and placenta, Biology

Assignment Help:

Extra-Embryonic Membranes and Placenta

The extra embryonic membranes like you already know provide nourishment and protection. These membranes are fundamentally similar to the extra-embryonic membranes of reptiles and birds, however the method of origin differs in humans. During the third and fourth week, the amnion grows around the embryo enclosing it in a membranous fluid filled sac in which the growing embryo and later the foetus floats and can move freely. This sac as mentioned in the previous section is a shock absorber and encloses a fluid, the amniotic fluid, that helps to keep the temperature of foetal environment stable. Another membrane, the chorion develops from the trophoblast cells. The chorion is a extremely specialised extraembryonic tissue. It facilitates the transfer of gases, nutrients and wastes among the embryo and the mother. It is the primary part of the placenta that we will study a little later. Yolk sac develops during the second week of development even though there is no yolk in the human egg. It does not give nourishment to the embryo but it becomes surrounded by mesoderm that forms the blood cells till the liver of the embryo becomes functional in the sixth week. The yolk sac with the allantois forms the umbilical cord. Part of the yolk sac also forms the lining of the gut. The allantois that forms during the third week of development is a tiny sausage shaped pouch on the yolk sac. It also is accountable for producing blood cells and later develops into the umbilical blood vessels.


Related Discussions:- Extra-embryonic membranes and placenta

What characteristics of fatty acids are false, what characteristics of fatt...

what characteristics of fatty acids are false? (Dissolves in water, used for energy storage, used to build lipids, found in triglycerides, found in steroids)?

Fission - asexual reproduction, Normal 0 false false false ...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

The eye refract the light, Which parts of the eye refract ('bend') the ligh...

Which parts of the eye refract ('bend') the light in such a way as to form an image on the retina?   The curved surface of the cornea, and the aqueous humour enclosed by it,

Define minerals, Define minerals Definition of minerals, as it applies ...

Define minerals Definition of minerals, as it applies to food and nutrition usually refers to  the elements other than carbon, hydrogen, oxygen and nitrogen that are present in

What is an open circulatory system, What is an open circulatory system? ...

What is an open circulatory system? Open circulatory system is the one in which blood does not circulate only in blood vessels but it also falls in cavities that irrigate tissu

Guanine, Guanine is one of the nitrogenous bases in the nucleic acids, gua...

Guanine is one of the nitrogenous bases in the nucleic acids, guanine is one of the two purine bases.

Endocrine organs, Endocrine Organs Endocrine organs, as explained ear...

Endocrine Organs Endocrine organs, as explained earlier are those organs or tissues, which release chemical substances directly into blood stream. Not like exocrine glands th

Effect on water bodies - dissolved oxygen (do), Effect on Water Bodies - Di...

Effect on Water Bodies - Dissolved Oxygen (DO) Most aquatic, organisms respire with oxygen dissolved in water. The quantity of dissolved oxygen in a unit volume of aerated wa

Experiments of dobzhansky and spassky, Theodosius Dobzhansky and Boris Spas...

Theodosius Dobzhansky and Boris Spassky demonstrated the working of normalising selectioion a behavioural trait in two populations of Drosophida pseudobscura. The two populatiors w

Biosynthesis of hemes and chlorophylls, In animals, some of bacteria and fu...

In animals, some of bacteria and fungi, and the first step in tetrapyrrole synthesis is the condensation of the amino acid glycine with succinyl  CoA (an intermediate  of the citri

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