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

Equipment and supplies -pre-requisite of nursing unit, Equipment and Suppli...

Equipment and Supplies: Nurses who are aware of location of equipment and supplies do give accurate delivery of patient care without delay and wastage of  time and energy for

How are lipids used as an energy source by the organism, How are lipids use...

How are lipids used as an energy source by the organism? Carbohydrates are the major energy source for aerobic cell respiration. In the absence or deficiency of such substances

Thumb rule for dietary management, Q. Thumb rule for dietary management? ...

Q. Thumb rule for dietary management? The thumb rule for dietary management is to advice the patient to try to cut down or avoid:  Red meats. Organ meats such as br

Horizontal chart - organization chart, Horizontal Chart: Horizontal ch...

Horizontal Chart: Horizontal chart which read from left to right are occasionally used. The pyramid lies horizontally instead of standing in the vertical position. The line of

Differences between prokaryotic & eukaryotic cells, DIFFERENCES BETWEEN PRO...

DIFFERENCES BETWEEN PROKARYOTIC & EUKARYOTIC CELLS   S . N o .   CHA R AC T ERS   P R O K AR Y O T I C CELL

How does the intensity of facilitated diffusion differ, Q. How does the int...

Q. How does the intensity of facilitated diffusion differ in relation to the concentration of the moved substance? What is limiting factor? Like simple diffusion facilitated di

Describe insulin resistance in non-conventional factors, Describe Insulin r...

Describe Insulin resistance in Non-conventional Factors ? Insulin resistance refers to a generalized metabolic disorder in which various tissues are resistant to normal levels of

How alkaline cleaning compounds works, Q. How Alkaline cleaning compounds w...

Q. How Alkaline cleaning compounds works? Carbonates, bicarbonates, hydroxides of various metals are called alkaline compounds. Alkaline cleaning compounds have a pH between

Direct vs. indirect competition model, Pikas (component 1), also known as "...

Pikas (component 1), also known as "rock rabbits" or "coneys", are small relatives of rabbits belonging to the genus Ochotona. The 30 species in this genus are confined to high alt

How do populations of predators vary in predatism, How do populations of pr...

How do populations of predators and prey vary in predatism? Whenever a predator population enhances at the first moment the prey population tends to decrease. At a second momen

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