Third week - embryonic development, Biology

Assignment Help:

Third Week - Embryonic Development

Throughout the third week of development the ICM separates from the uophoblast and forms the flattened embryonic disc, which at first consists of cells of all three germ layers, ectoderm, endoderm and mesoderm and is termed as the epiblast. From this a lower layer separates to form the endoderm. The second layer, mesoderm, forms through the migration of cells through the primitive streak that forms as the embryonic disc elongates. The cells remaining in the upper layer make the ectoderm. These three germ layers will give rise to all the organs of the body as pointed out in Figure.

2006_Third Week.png

Figure: The organs of the body form from the three germ layers

The embryo's heart as well begins its development as a pair of microscopic tubes. The cardiovascular system is the first system to become functional in the embryo. At the end of the 3rd week the heart tubes fuse and become linked to the blood vessels in the embryo, body stalk, chorion and yolk sac, to make a primitive blood circulatory system. Chorionic villi (that will form the placenta later) also begin to form during this period.


Related Discussions:- Third week - embryonic development

Behavioural adjustments, Behavioural Adjustments When faced with a su...

Behavioural Adjustments When faced with a sudden temperature change, most animals make behavioural responses that enable them to avoid extreme or lethal conditions. Among the

Ecology.., write the charecteristics of lake ecosystem

write the charecteristics of lake ecosystem

Explain control of oedema in nutritional care, Explain Control of Oedema in...

Explain Control of Oedema in Nutritional Care? Low levels of circulating proteins lead to oedema due to loss of colloidal osmotic pressure to maintain the normal fluid shift me

What is recombination frequency, What is recombination frequency? Recom...

What is recombination frequency? Recombination frequency, or crossing over rate, is the percentage of recombinant gametes made by crossing over (in relation to the number of pa

Virus is in an inactive state, Q. What is signifying when it is said that a...

Q. What is signifying when it is said that a virus is in an inactive state? Viruses considered in inactive state are those whose genetic material is within host cells without a

Define protection against poisoning - function of vitamin e, Define Protect...

Define Protection against poisoning - Function of Vitamin E? 1) Protection against poisoning: It protects liver from injury due to carbon tetra chloride poisoning. 2) Pr

Define the term - functional magnetic resonance imaging, Define the term - ...

Define the term - Functional magnetic resonance imaging Functional magnetic resonance imaging (fMRI) is a recent development that permits simultaneous measurements of the brain

What is the kind of circulatory system present in annelids, Q. What is the ...

Q. What is the kind of circulatory system present in annelids? In beings of the phylum Annelida the circulatory system is closed that is blood circulation takes place only with

What is nervous system, What is Nervous System? The nervous system is m...

What is Nervous System? The nervous system is made up of associations of cells called neurons. Bundles of neurons are called nerves. The nervous system is divided into two part

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