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

Name the associated foods used in bacillus cereus, Name the Associated Food...

Name the Associated Foods used in bacillus cereus  Cereal dishes that contain corn and corn starch, mashed potatoes, vegetables, minced meat, liver sausage, milk, cooked meat.

List disbeliefs which patients have about insulin, Q. List disbeliefs which...

Q. List disbeliefs which patients have about insulin? a) Insulin is not effective. Some patients believe that insulin is not effective for treating diabetes. b) Insulin c

Chemical properties of soil, CHEMICAL PROPERTIES OF SOIL Soil is a high...

CHEMICAL PROPERTIES OF SOIL Soil is a highly dynamic system which supports complex chemical reactions. In this heterogeneous systems, the soil solution acts as the medium for c

Water of estuaries, Water of Estuaries The water of estuaries is turbi...

Water of Estuaries The water of estuaries is turbid because of the great number of particulates in suspension in the water. The turbidity is minimum near the mouth and increas

Cell wall, Cell wall is the structure produced by some of the cells outsid...

Cell wall is the structure produced by some of the cells outside their cell membrane; variously composed of the chitin, peptidoglycan, or cellulose.

Draw decanol, Draw decanol, plamitic acid (C16:0 fatty acid) and the result...

Draw decanol, plamitic acid (C16:0 fatty acid) and the resulting wax ester generated by a dehydration reaction between both molecules.

Explain etiology and clinical feature of parkinson''s disease, Explain the ...

Explain the Etiology and Clinical Features of Parkinson's disease? The cause of Parkinson's is unknown. Genetic predisposition (in most cases the reason for the death of these

What is the parasite that causes giardiasis, Q. What is the parasite that c...

Q. What is the parasite that causes giardiasis? How is it transmitted and what are the typical manifestations of the disease? The Giardiasis is a protozoal infection caused by

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