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!
Spiral Cleavage - Metazoa
In Spiral Cleavage, however, the third and fourth cleavage planes are oblique to the polar axis and the resulting blastomeres do not lie on top of one another but above the furrows between the cells. The spindles during the third cleavage are arranged in the form of a spiral, therefore, the name spiral cleavage. This type of cleavage is seen in all invertebrate except the echinoderms (i.e. in annelids, molluscs, arthropods nemertenes and polyclad planarians).
Figure: Spiral cleavage showing transition from 4 to 8 to 16 cell stage
Spirally cleaving embryos are said to have mosaic or determinate form of development. This means that the organ forming regions of the egg are strictly localised in the egg from the very beginning and the fate of the blastomeres is determined early. If the blastomeres are separated, each will continue to develop up to a certain time as though it was a part of the whole and give rise to defective, partial embryos. In the early embryos an unidentified cytoplasmic factor is segregated into one of the blastomeres, the mesentoblast (this is also called the '4 d' cell) which gives rise to the future mesoderm.
diff b/w protonephridia and metanephridia
What are the Consequences of PEM? The consequences of PEM are most often long lasting and irreversible. The common consequences include: • Irreversible growth retardation
what is hybridization,and what are its different types??
What are the main representatives of the pteridophytes? Is this plant group cryptogamic or phanerogamic? The better known pteridophytes are the ferns and the maidenhairs, from
Imagine a population evolving by genetic drift in which the frequency of allele K is 0.65. What is the probability that at some point in the future allele K will drift to a frequen
Q. Symptoms of Angina Pectoris? The pain of angina is usually over the center of the chest (below the sternum) but can be felt from epigastrum to the jaw and arms. It is brough
Effects on plants of Air pollutants SO 2 , O 3 and NO 2 are strong oxidants and can bring about significant changes in plant cell chemistry. The general effects of pollutant
respiration
Protozoa classification
Osmotic pressure is the pressure formed in a aqueous solution by a region of lower solute concentration upon a region of superior solute concentration forcing the passage of water
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