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.

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 3^rd 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.

Posted Date: 2/1/2013 4:57:11 AM | Location : United States

Ask an Expert

Related Discussions:- Third week - embryonic development, Assignment Help, Ask Question on Third week - embryonic development, Get Answer, Expert's Help, Third week - embryonic development Discussions

Write discussion on Third week - embryonic development
Your posts are moderated

Write your message here..

Related Questions

Determinants of vascular tone, The vascular tone increases as the arterial ... The vascular tone increases as the arterial size decreases. The tone at any time reflects the effects of excitory and inhibitory pathways. Neurotransmitters, physical forces like s

State about the neuropsychological assessment, State about the Neuropsychol... State about the Neuropsychological assessment Neuropsychological assessment provides information concerning the status of brain function across the life span. It does so primar

Transcription in prokaryotes, As in several fields of molecular biology stu... As in several fields of molecular biology studies of E. coli have gives the model for subsequent investigations of transcription in eukaryotic cells. The basic mechanisms by that t

Cytokinins and Cell Division, α - amylase activity by GA 3 - Dormancy ... α - amylase activity by GA 3 - Dormancy Of the enzymes required for the digestion of starch α-amylase appears immediately after the start of germination. It was found that

Pathophysiology and medical mangement of acute renal failure, Pathophysiolo... Pathophysiology of Acute Renal Failure It is usually reversible but the deviation of physiologic function can be extreme and mortality in pediatric age group remains high. Th

Cobalt deficiency, Cobalt deficiency The deficiency of cobalt is more ... Cobalt deficiency The deficiency of cobalt is more commonly seen in ruminants fed on diets deficient in this essential micronutrient. Cobalt is stored only in limited amounts

Define the contraceptive morbidity, Define the Contraceptive Morbidity ... Define the Contraceptive Morbidity Contraceptive morbidity, which covers any condition that result from efforts (other than abortion) to limit fertility, whether they are tradi

Zoonoses disease-monkey pox, Monkey pox Monkey pox is caused by Monkey pox... Monkey pox Monkey pox is caused by Monkey pox virus, a member of genus Orthopoxvirus. Transmission generally occurs as a result of close contact with infected animals, mostly thro

Which of the groups is not ionizable, Which of the following groups is NOT ... Which of the following groups is NOT ionizable? Select one: a. Guanidinium b. Imidazole c. Phosphoryl d. Amine e. Aldehyde

Define about the classification of polyphenols, Define about the Classifica... Define about the Classification of polyphenols?  The various classes are: a) Phenolic acids and derivatives b) Flavonoids such as Flavonols and Flavones, Isoflavones and