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

Fungi, Which type of reproductive structure has a better chance of survival...

Which type of reproductive structure has a better chance of survival if there was a sudden temperature change in its environment?

What is replication, Question 1 Write a short note on the following- ...

Question 1 Write a short note on the following- Structure of DNA. Satellite DNA Transcription. pBR 322 vector Cytokines Microarrays Question 2 What is

Mechanisms that affect the heart rate, Mechanisms that Affect the Heart Rat...

Mechanisms that Affect the Heart Rate Two different mechanisms affect the heart rate. Nerve impulse to the pacemaker region and hormonal influences. A branch of the vagues ner

Patient and probe positioning, Patient Positioning The patient  should...

Patient Positioning The patient  should be  in  the  left lateral position as  this brings the heart into contact with chest wall. The left arm is extended behind  the head  t

Name the animal who have its own dna, Which one of the following has its ow...

Which one of the following has its own DNA? 1. Mitochondria 2. Dictyosome 3. Lysosome 4. Peroxisome Mitochondria

Temperature regulation in homeotherms, Temperature Regulation in Homeotherm...

Temperature Regulation in Homeotherms Homeothermy is regulation of body temperature by physiological means. The stabilisation of body temperature permits a steady high level

Determine the term epitheliomuscular cell, Determine the term Epitheliomusc...

Determine the term Epitheliomuscular cell. Cells which line outer surface of cnidarians. These cell have two functions: first is to form the outer body covering of animal, seco

Define physiologic functions of iodine, Define Physiologic Functions of Iod...

Define Physiologic Functions of Iodine? Thyroid hormone performs multiple functions as regulator of cell activity and growth. The hormone has crucial metabolic roles in the foe

Etiological factor of dyspepsia, Q. Etiological factor of dyspepsia? Th...

Q. Etiological factor of dyspepsia? The main etiological factor of dyspepsia is the failure of proper digestion and absorption of food in the alimentary tract and the consequen

Marine animals, Marine Animals The composition of body fluids of mari...

Marine Animals The composition of body fluids of marine invertebrates, including the ascidians are similar to seawater. Such animals need not expend much energy in regulating

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