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

Determine the increase in the length of the right knee, What is the respons...

What is the response to enhance in the length of the right knee extensors in response to a quick tap applied to the right patellar tendon?  An increase in the amount of    A. o

Define historical example of virulence, Define Historical example of virule...

Define Historical example of virulence? The "classical dogma" of epidemiologists was that pathogens all the time evolve in the direction of lower virulence, eventually becoming

Define the bacillus cereus, Define the Bacillus cereus Bacillus cereus ...

Define the Bacillus cereus Bacillus cereus is not a common cause of food poisoning. It is a Gram positive, aerobic, spore forming rod shaped bacteria normally present in soil,

Coding sequence, Coding sequence is the portion of the gene or the mRNA wh...

Coding sequence is the portion of the gene or the mRNA which actually codes for a protein. Introns are not coding for the sequences; nor are the 5' or 3' untranslated regions (or

In which bones can bone marrow chiefly be found, In which bones can bone ma...

In which bones can bone marrow chiefly be found? Is the bone marrow made of osseous tissue? Bone marrow can mostly be found in the internal cavities of flat bones, as the verte

What are passive and active immunization, What are passive and active immun...

What are passive and active immunization? According to the duration of the protection how do these types of immunization differ? Active immunization is that in which an antigen

Define behaviour modification - combat from obesity problem, Define Behavio...

Define Behaviour modification - combat from obesity Problem? It is very important. A heavy parental hand and parent attitude and behaviours towards child's eating, interferes i

What is limnetic zone, Q. What is limnetic zone? The open water zone is...

Q. What is limnetic zone? The open water zone is called the limnetic zone. This represents the zone or depth of the water upto which sunlight can penetrate. Phytoplankton along

Define manganese metabolism - micro minerals, Define Manganese Metabolism -...

Define Manganese Metabolism - Micro Minerals? Intestinal absorption of Mil occurs throughout the length of the small intestine although the exact mechanism of absorption is not

Can you define striated cardiac muscle tissue, Q. Of which kind of tissue i...

Q. Of which kind of tissue is the heart made? How is this tissue oxygenated and nutrified? The heart is made of striated cardiac muscle tissue and the heart muscle is called th

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