Emboly - mechanism of gastrulation, Biology

Assignment Help:

EMBOLY -

The embolic morphogenetic movements are concerned with the inward migration of prospective endodermal and mesodermal blastomeres from the external surface of blastula.

The movement of mesodermal and endodermal blastomers may take place by any of the follwoing methods -

(i) Invagination -

  1. It is the easiest way to gastrulation. It is the process in which the cells from the vegetal side of blastula sinks in or move downwards or are pushed into the interior of blastocoel.
  2. Thus blastocoel becomes smaller and smaller as the invagination gets higher, and a new cavity is formed which is called Archenteron cavity. This archenteron cavity forms the mesenteron of alimentary canal.
  3. The apperture of archenteron cavity is called blastopore.
  4. This blastopore gives rise to mouth in protostomia animals e.g. Helminthes Annelida, Mollusca tec.
  5. In some animals blastopore gives rise to the anus. e.g. Deuterostomians.
  6. Complete gastrulation in amphioxus takes place by invagination.
  7. Invagination is also found in frog.
  8. The megameres of blastula of frog undergo invagination and become bottle-shaped and protrude inside the blastocoel.

797_invagination.png

(ii) Involution -

  1. It is the Rolling movement of the blastomeres from the surface to the inner side of the embryo.
  2. In frog, mesoderm & endoderm are formed by involution.
  3. All the micromeres divide and reach the dorsal-lip of blastopore.
  4. The collective movement of blastomeres towards common point is termed as convergence.
  5. From here the blstomeres enter inside the blastocoel cavity while performing the rolling movement.This is termed as involution.
  6. As a result of involution, the blastocoel cavity is completely obliterated and a new cavity archenteron is formed.

1117_involution.png


Related Discussions:- Emboly - mechanism of gastrulation

Transmissible gastroenteritis of swine, Transmissible gastroenteritis of sw...

Transmissible gastroenteritis of swine The disease, first reported from the USA in 1964, is caused by antigenic group 1 mamalian coronavirus, a member of genus Coronavirus of

Define important food sources of protein, Define Important Food Sources of ...

Define Important Food Sources of Protein? The important sources of proteins in the diets of low-income groups are cereals and legumes. Meat, fish, eggs and milk are important s

What kind of eye defect can give rise to short-sightedness, What kind of ey...

What kind of eye defect can give rise to short-sightedness? Long eyeballs, large eyeballs, too powerful a lens or a combination of these defects can give increase to short-sigh

What is anatomic concavities, What is Anatomic concavities Anatomic co...

What is Anatomic concavities Anatomic concavities present in the lingual surface of the mandible, the sublingual fossa anteriorly and the submandibular fossa posteriorly. Norm

Explain the colorimetric method glucose estimation, Explain the Colorimetri...

Explain the Colorimetric Method Glucose Estimation? Alkaline copper reduction methods are by far the most commonly used methods for glucose estimation. This time honoured metho

Working of serotonergic cell bodies, Q. Working of serotonergic cell bodies...

Q. Working of serotonergic cell bodies? The major site of serotonergic cell bodies is in upper pons and the midbrain, specifically the median and dorsal raphe nuclei and to a l

Branchiostoma, What is the feeding habitat of branchiostoma?

What is the feeding habitat of branchiostoma?

Foot examination for an diabetics, Foot examination For all diabetics, ...

Foot examination For all diabetics, foot examination is important and necessary in all visits to identify risk factors of ulcers or injury of foot. This will help in preventing

Temperature and concentration of nutrients, Temperature and Concentration o...

Temperature and Concentration of Nutrients Temperature Temperature like salinity remains almost constant in the oceans in contrast to the land or terrestrial ecosystems

Invertebrates, #question.3 different genera of invertebrates

#question.3 different genera of invertebrates

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