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 do energy pyramids represent, Q. What do energy pyramids represent? ...

Q. What do energy pyramids represent? The Energy pyramids represent the amount of accessible energy in each trophic level of the food chain.

Growth rate in animals, GROWTH RATE IN ANIMALS - Growth rate is differe...

GROWTH RATE IN ANIMALS - Growth rate is different at different periods of life. Growth period in human may be studied in 5 steps - (i) Prenatal - In gestation period fo

How are the sensory receptors classified, Q. According to the stimuli they ...

Q. According to the stimuli they collect how are the sensory receptors classified? The sensory receptors are classified according to the stimuli they get: mechanoreceptors are

Phylum protozoa, #question.unique features of amoeba.

#question.unique features of amoeba.

What is the definition of ecology explain, What is the Definition of Ecolog...

What is the Definition of Ecology explain? Scientists use the term ecology to refer to the study of the relationships between organisms, and the relationships between organism

Where does the water resorbed after glomerular filtration, Q. Where does mo...

Q. Where does most of the water resorbed after glomerular filtration go? What are the other substances resorbed by the nephron tubules? Only 0.5 to 1% of the glomerular filtrat

How many are the known amino acids, How many are the known amino acids that...

How many are the known amino acids that form proteins in living beings? There are twenty dissimilar known amino acids that form proteins related to the genetic code of the livi

Is protein collagen has a high proportion of glycine, The protein collagen ...

The protein collagen has a high proportion (20% or more) of A. asparagine and glutamine B. proline and hydroxyproline C. glycine D. both A and B E. both A and C F

Define about the spectral techniques - colorimetry, Define about the Spectr...

Define about the Spectral Techniques - Colorimetry? Many determinations in the biochemistry laboratory are based on measurements of radiant energy emitted, transmitted, absorbe

Mechanism of gastrulation, MECHANISM OF GASTRULATION - It is most im...

MECHANISM OF GASTRULATION - It is most impotant stage of embryonal development, in which single layered blastula converts into 2 or 3 layered gastrula. During this stage,

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