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.
S y s te m i c Diseases Diseases of the gastrointestinal tract The diseases of gastrointestinal system are manifested by abnormality in prehension, mastication and s
Cellular Totipotency The innumerable cells which constitute the body of a higher plant or animal and containing identical genetic material can be traced to a single cell-the
1. Biogas is produced by the activity of aerobic bacteria on animal waste 2. Methanobacterium is an aerobic bacterium found in rumen of cattle 3. Biogas, commonly called goba
Define Advantages of using Bacteria as a source of protein? Advantages of using Bacteria as a source of protein are as follow: 1. High yield of protein (60-80%) 2.
Q. What is Short Bowel Syndrome? Short bowel syndrome is a group of problems affecting people who have /had half or more of their small intestine removed. The massive resection
Endocytosis is the uptake of extracellular macromolecules across the plasma membrane into the cell. The objects to be ingested is progressively enclosed by a small portion of
Q. Various types of microorganisms? Microbes are single-cell organisms so tiny that millions can fit into the eye of a needle. They are the oldest form of life on earth. Micro
Even though association between GAS pharyngitis and the ARF is fairly well established, the exact pathogenic mechanisms are not clearly understood. However, two mechanisms are post
Determine the Requirement of carbohydrate for Endurance Events? For endurance events like sprinting (100 m run), football, hockey, the carbohydrate intake can be placed at 7:10
Urine Normal urine is clear, yellow in colour, slightly acidic. Urine consists of 96% water and 4% solids like urea, uric acid, urates, chlorides, phosphates, oxalates, sulphat
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: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd