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

Agro industrial-by-products from sugar industry, By-Products from Sugar Ind...

By-Products from Sugar Industry India is one of the important sugarcane (Saccharum officinarum) growing countries of the world. Five main by-products are available from the su

Antiparkinsonian drugs, Antiparkinsmian Drugs: Antiparkinsonian drugs ...

Antiparkinsmian Drugs: Antiparkinsonian drugs are  the  specific drugs  to treat the extrapynnidal side effects  of  antipsychotic agents.  Anticholinergic drugs  block

Explain trapezoidal full mucoperiosteal flaps, Explain Trapezoidal Full Muc...

Explain Trapezoidal Full Mucoperiosteal Flaps a) Similar to rectangular flap except: The 2 vertical incisions are at obtuse angle with the Horizontal incision, b) Mostly

Explain about the chromium metabolism, Explain about the Chromium Metabolis...

Explain about the Chromium Metabolism? Chromium appears to be absorbed throughout the small intestine, with absorption being higher in jejunum. The mechanism of absorption has

Evolutionary species concept, The evolutionary species concept which ident...

The evolutionary species concept which identifies a species as a "lineage (i.e. ancestor descendant sequence of population) evolving separately from others with its own unitary ro

Cardiac cycle, The term cardiac cycle means one pumping cycle which consist...

The term cardiac cycle means one pumping cycle which consists of contraction (systole) and relaxation (diastole) of both the atria and both ventricles. Both the atria contract at t

Retention of water by kidneys, Retention of water by the kidneys is regulat...

Retention of water by the kidneys is regulated by a part of the brain, called the hypothalamus, that controls the secretion of antidiuretic hormone (ADH).An increased secretion of

Ecology, Importance of ecology

Importance of ecology

Define iron status of the individual, Define Iron Status of the Individual ...

Define Iron Status of the Individual Lastly, iron status of the individual is a floury determinant of how much iron is absorbed. On a mixed diet with some haem iron, the overal

Define etiology and clinical features of epilepsy, Define Etiology and Clin...

Define Etiology and Clinical Features of Epilepsy? This disorder usually starts in childhood, with the peak incidence between birth and two years. Etiological factors include

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