Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
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.
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.
Q. What is phosphorylation? What are various biological processes in which phosphorylation plays a critical role? Phosphorylation is the name given to procedure of the addition
Why are producers the first trophic level to advantage from the activity of decomposers? Decomposers return nutrients in dead tissues and wastes to the soil or water; producers
Air pollution affects both living and non-living matter. The effects can be classified as.
Tingling or numbness is seen in cases of neuropathy. It occurs gradually over time. As high sugar (glucose) in the blood damages the nervous system, particularly in the extremities
Mandibular Ramus Serves as an intraoral autogenous bone donor site. Cortical bone upto 4mm thickness may be harvested from the ramus. Harvest of bone from this area requires kn
Ideal Characteristics 1) Maximize gas transfer (oxygen, carbon dioxide and anaesthetic gases) 2) Minimize blood trauma 3) Good heat transfer efficiency 4) Minimize
Mechanical Valves They are made of a combination of metal alloys, pyrolite carbon and dacron. Types of Mechanical Valves Caged-ball Valve (Star-Edwards) A me
Indications for Surgery : The normal mitral valve area is 4-5 cm 2 . Usually symptoms appear when the valve area has become less than 2.5 cm2. Symptoms are present at rest when t
Hydrogen Transferring Coenzymes This group consists of three important coenzymes all of which assist different enzymes in oxidation-reduction reactions. These are: a
what is biological sickness of soil and its management
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!
whatsapp: +1-415-670-9521
Phone: +1-415-670-9521
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd