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

Food gathering and hunting , Food Gathering and Hunting : Food Gatherin...

Food Gathering and Hunting : Food Gathering and Hunting In order to live, man needed to eat and to protect himself from the weather and animals.  For both purposes he found it

Factors influencing metabolism, Let us learn about the factors that affect ...

Let us learn about the factors that affect metabolism: 1) More energy is required when muscular work is carried out. 2) The larger the surface area of the body, more heat is

Define steps in the development of exchange list, Define Steps in the Devel...

Define Steps in the Development of Exchange List? As mentioned above, when we group together similar food items so that each supplies a constant amount of a particular nutrient

Explain anabolic reactions, Anabolic reactions: The  intermediates of citr...

Anabolic reactions: The  intermediates of citric acid cycle are used  as precursors  in tlie biosynthesis of many compounds  like synthesis of glucose  from carbon skeletons of am

Explain amylase, Amylase The presence of pancreatic amylase brings abou...

Amylase The presence of pancreatic amylase brings about  the breakdown  of starch  and glycogen and  its action is similar to salivary amylase. The hydrolysis of  starch and gl

Define nutritional management of neurological disorders, Define Nutritional...

Define Nutritional Management of Neurological Disorders Your friend's aged father, over a period of time has become very confused, forgetful and is unable to do many things he

Stratification, Stratification On the basis of the variation in air tem...

Stratification On the basis of the variation in air temperature. the atmosphere has been divided vertically into four layers: (figure shown below) thee troposphere, stratospG,

Explain fibre and cardiovascular disease (cvd), Explain Fibre and Cardiovas...

Explain Fibre and Cardiovascular Disease (CVD)? The role-of dietary fibre in modulation of blood lipids was demonstrated by Keys and his co-workers in a series of experiments c

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