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

What is iodoacetate inhibitor, What is Iodoacetate inhibitor Iodoacetat...

What is Iodoacetate inhibitor Iodoacetate is the inhibitor of glyceraldehyde-3-phosphate  dehydrogenase.

Rbc & wbc, difference between RBC and WBC for homework

difference between RBC and WBC for homework

Zoology, differences regarding Tiger Planaria and the Iridescent Phyllodoce...

differences regarding Tiger Planaria and the Iridescent Phyllodoce

Needle and sharp instrument safety, Needlestick/sharp instrument injuries a...

Needlestick/sharp instrument injuries are of major concern to health care workers. All of the significant exposures reported in the academic year 2003/04 in our Faculty, were injur

Can you explain radula, Q What is the radula? What is the function of this ...

Q What is the radula? What is the function of this organ? Some molluscs have a tongue-like structure with harsh saliences similar to small teeth. This structure is called as ra

Electron transport and oxidative phosphorylation, Many of the free energy f...

Many of the free energy free during the oxidation of glucose to CO 2 is retained in the decreasing coenzymes NADH and FADH 2 producing while glycolysis and the citric acid cycle.

Characteristics of population, CHARACTERISTIC S OF POPULATION - Each p...

CHARACTERISTIC S OF POPULATION - Each population envolves adaptations suited to its own locality. Population is unit of evolution. Population is also an ecological uni

Explain composition of human milk, Explain Composition of Human Milk? R...

Explain Composition of Human Milk? Research clearly shows that each type of mammalian milk is unique and consists of a highly complex mixture of organic and inorganic compounds

Chloroplasts , Chloroplasts Like mitochondria, chloroplasts are also di...

Chloroplasts Like mitochondria, chloroplasts are also distinctive organelles of eucaryotic cell. But they are found only in plant cells. Chloroplasts contain membranes forming

Explain what is mortality in coronaw artery disease, Explain what is Mortal...

Explain what is Mortality in coronaw artery disease ? Marked prematurity and extensive atherosclerosis leads to markedly higher mortality in young Asian Indians compared to oth

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