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.
Explain Kashin Beck disease caused by selenium deficiency? Kashin Beck disease was identified to affect growing children in parts of Siberian Russia and China. It is characteri
which bone of rabbit is like wing?
economic importance of oblia
Define the Over nutrition obesity of Infant? An infant is never put on a reducing diet. The chances of obesity are least if an infant is exclusively breast-fed till 6 months. I
Class adverse effects of NNRTI All NNRTIs can cause a rash that is sometimes severe. NNRTIs are metabolized by and can affect hepatic CYP 450 isozymes; drug interactions can o
how do humans reproduce?
What is the function of the myelin sheath? Do all axons present a myelin sheath? The function of the myelin sheath is to get better the safety and speed of the neural impulse t
Gene targeting: There is always a debate on gene integration in to the host animal. It is random gene integration Vs gene targeting. Perhaps most significantly, pro-nuclear in
how do honey bees breathe
Q. What are some representatives of the echinoderm phylum? Starfishes, sea urchins, sea cucumbers (holothurians) and brittle stars are examples of echinoderms.
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