Fate of blastopore, Biology

Assignment Help:

Fate of Blastopore

Cleavage results in the formation of a ball of cells called morula (resembling mulberry hence the name). A space appears in the morula changing it to a hollow blastula. The central cavity is called the blastocoel and the layers of cells surrounding it the blastoderm. Invagination or infolding of the blastoderm gives rise to a double walled gastrula. The cavity of this double walled cup is called archenteron and the opening of the archenteron to the outside is called the blastopore.

2395_Fate of Blastopore.png

Figure: Early embryology of a nemertean worm a protostome

As the gastrula develops further, 'parts of the embryo give rise to different structures to ultimately form a complete young one. In platyhelminths, nematodes, annelids, arthropods and molluscs that have spiral cleavage, the embryonic blastopore forms the mouth of the animal and the anus is formed secondarily. Because the mouth forms first these animals are included in 'Protostomia' (mouth first) division of Animal Kingdom. In echinoderms, chaetognaths, hemichordates and chordates where radial cleavage takes place, the blastopore forms the anus of the animal and the mouth is formed secondarily, as an independent opening on the body wall as seen in Figure. Therefore, these animals are included in 'Deuterostomia' (mouth second), division of the Animal Kingdom.

The fate of the blastopore thus determines two fundamental lines of evolution. The protostomes in which the cleavage is generally mosaic (determinate and spiral) and the Deuterostomes in which the cleavage is usually regulative (radial and indeterminate) type.


Related Discussions:- Fate of blastopore

Glucose-1-phosphate to glycogen, Glucose-1-phosphate to Glycogen The co...

Glucose-1-phosphate to Glycogen The conversion  of glucose-1-phosphate  to glycogen  is  through UDPG and glycogen synthase. We shall learn about  this later in section under g

Lung biopsy, Lung Biopsy: As with pleural biopsy,  lung biopsy may  be  d...

Lung Biopsy: As with pleural biopsy,  lung biopsy may  be  done by  surgical exposure of the lung (open lung biopsy) with or without endoscopy using a needle designed to remove a

Discuss about brain, Brain Brain is a part of central nervous system wh...

Brain Brain is a part of central nervous system which lies in the skull. Source: Sears and Windwood, Anatomy and Physiology for Nurses The different parts of the bra

Dinoflagellates, Dinoflagellates are single-celled to colonial protistans ...

Dinoflagellates are single-celled to colonial protistans characterized by the two flagella, one girdling cell and the other trailing the cell. Some of the dinoflagellates exist in

Explain the ecological approach in taxonomy, Explain the Ecological Approac...

Explain the Ecological Approach in Taxonomy You already known that the use of ecological data in classification has been used since the time of Plato who considered aquatic, te

Explain the techniques of operation in post myocardial, Explain the Techniq...

Explain the Techniques of Operation used in post myocardial infarction ventricular septal defect? Normal 0 false false false EN-IN X-NONE X-NONE

Which terrestrial vertebrate group is extremely rare deserts, Which terrest...

Which terrestrial vertebrate group is extremely rare in deserts? The Amphibians are terrestrial vertebrates very rare in desert environments (although there are a few species a

Define carbohydrate requirements for physical fitness, Define Carbohydrate ...

Define Carbohydrate Requirements for Physical Fitness? Carbohydrate is the primary fuel for high intensity exercise, Increased intake of carbohydrate on a consistent basis enab

Describe about pulmonary respiration, Q. Besides vertebrates two invertebra...

Q. Besides vertebrates two invertebrate phyla contain species that make pulmonary respiration. Which are these phyla? Terrestrial molluscs and the arachnid arthropods are the i

Natriuretic peptides, There are three natriuretic peptides-atrial (ANP) sto...

There are three natriuretic peptides-atrial (ANP) stored mainly in the atrium, brain (BNP) stored mainly in the ventricular myocardium and C-natriuretic peptide (CNP) located prima

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