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

How are the epithelial tissues classified, Q. How are the epithelial tissue...

Q. How are the epithelial tissues classified? The epithelial tissues are classified according to the shape of the cells that form it epithelial cells may be columnar, cuboidal,

Gene interactions (post mendelian genetics), GENE INTERACTIONS (POST MENDEL...

GENE INTERACTIONS (POST MENDELIAN GENETICS) Phenotypic expression of a gene may be altered by the influence of other genes. The modification of the normal phenotype of certain

Describe the external features of the heart, Question 1 Describe the exter...

Question 1 Describe the external features of the heart. Add a note on circulation of blood within the heart Question 2 Discuss the major joints of thorax and pelvis Quest

Define class – arachnida, Define Class – Arachnida? The class Arachnida (...

Define Class – Arachnida? The class Arachnida (Arachnida = spider) has terrestrial and few aquatic animals. It includes spider, scorpions and mites. 1. Prosoma bears. six pair

Pulmonary edema, Pulmonary edema occurs when movement of liquid from the bl...

Pulmonary edema occurs when movement of liquid from the blood to the interstitial space and/or into the alveoli exceeds the return of liquid to the blood and its drainage through t

Glucagon and glucocorticoids, Important  aspects  related to regulation inc...

Important  aspects  related to regulation include: 1)  The hormones glucagon and glucocorticoids  which are  secreted  during  starvation stimulate  glucose-6-phosphatase to en

Explain indications for surgery of congenital pulmonary, Explain Indication...

Explain Indications for Surgery of Congenital Pulmonary Stenosis ? Interventional treatment is required for all neonates presenting with critical pulmonary valvar stenosis. Thi

What is a burette and how is it used, What is a burette and how is it used?...

What is a burette and how is it used? A burette is a uniform-bore glass tube with fine gradations and a stopcock at the bottom, used particularly in laboratory procedures for a

Phototheraphy and exchange transfusion, PHOTOTHERAPHY AND EXCHANGE TRANSFUS...

PHOTOTHERAPHY AND EXCHANGE TRANSFUSION: This section will enable you to acquire skills related to phototherapy and exchange transfusion. You will also review the indication

Plants and animals - biological weathering, Plants and animals The acti...

Plants and animals The activity of living organisms like lichens, fungi, bacteria, blue green algae, bryophytes is also responsible for weathering.  It is referred to as biolog

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