Gastrulation process - formation of primitive streak, Biology

Assignment Help:

Gastrulation Process - Formation of Primitive Streak

Gastrulation in all amniotes involving eutherian mammals is related to a characteristic structure termed as the primitive streak formed on the epiblast surface during the first 10-18 hours of incubation at 38.5°C temperature. It makes as a result of convergence of epiblast cells to the dorsal midline of the blastoderm. The starting of primitive streak formation is first pointed out by a thickening in the central posterior region of area pellucida immediately after the creation of hypoblast. The thickening narrows and elongates growing anteriorly in the centre of area pellucida. While fully formed the primitive streak is a narrow structure with a groove (Primitive groove) in its floor together its length flanked by a fold (or ridge) on either side. It extends anteriorly upon about three fourth the length of area pellucida in which it ends in a deep pit called Hensen's Node with thick borders.

During the formation of primitive streak the shape of area pellucida slowly changes from circular to pea shaped with the broad side anterior and narrow side posterior. This change is because of convergence of cells toward dorsal midline starting at posterior end and progressing anteriorly but stopping where the Hensen's Node is formed. With reference to the fate map it should be noted that the posterior end of the primitive streak would be in the centre of the posterior edge of the area of presumptive extra-embryonic mesoderm, and its anterior end (Hensen's Node) would be situated in the presumptive endodermal area posterior to notochordal area. Primitive streak marks the median anterior-posterior axis of the embryo and establishes bilateral symmetry.


Related Discussions:- Gastrulation process - formation of primitive streak

What is implant therapy, What is Implant therapy Successful implant th...

What is Implant therapy Successful implant therapy requires systematic thorough and meticulous planning to determine the ultimate prognosis and end result that will satisfy th

What are the chloroplasts, Q What are the chloroplasts? What are the major ...

Q What are the chloroplasts? What are the major functions of chloroplasts? Chloroplasts are organelles present in the cytoplasm of algae and plant cells, like mitochondria, chl

How does the heart impel the blood, Q. How does the heart impel the blood? ...

Q. How does the heart impel the blood? The heart is a muscular organ that contains chambers right ventricle and right atrium right ventricle and and left atrium through which b

Explain lipoprotein excess, Explain Lipoprotein (Lp(a) Excess ? While c...

Explain Lipoprotein (Lp(a) Excess ? While cholesterol and triglycerides are important lipid risk factors, another lipoprotein factor called Lipoprotein (a) is thought to play a

Explain bidirectional superior vena cavo, Explain Bidirectional Superior ve...

Explain Bidirectional Superior vena cavo pulmonary shunt bidirectional glenn "This is a palliative produce where blood from superior vena cava is diverted to the pulmonary arter

The osmolarity of the rbcs and plasma after equilibration, Ed Rivers, a 3rd...

Ed Rivers, a 3rd year medical student, was alone in the hospital ER one night. It was unusually quiet that night, and the resident was getting some much needed sleep. A patient, Mr

What are enzymes?, Enzymes are proteins that are catalysts of chemical reac...

Enzymes are proteins that are catalysts of chemical reactions. From Chemistry, it is called that catalysts are non-consumable substances that decrease the activation energy essenti

What do you meant by medical writing, Question 1 : What do you meant by ...

Question 1 : What do you meant by medical writing? Show various types of medical writing. Define and explain briefly medical writing Discuss various types of medical w

Explain some limitations of most probable number, Explain some Limitations ...

Explain some Limitations of Most Probable Number? 1. Large quantity of glassware is required. 2. Colony morphology cannot be determined. 3. It lacks precision.

Explain about metabolic diseases, Q. Explain about Metabolic diseases? ...

Q. Explain about Metabolic diseases? Metabolic diseases, as you already know, refer to those disorders in which the various reactions in the cells are effected (production of e

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