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.
PHYSIOLOG Y OF RESPIRATION - 1 . EXCHANGE OF GASES - It is Haemotasis. It takes place in Alveoli between alveolar air and arterial cappilary by diffusion i.e., f
composition formation and circulation of lymph
Insect resistant crops (IRC) Insects are a natural selection pressure so plants resistant to certain insects could have an evolutionary advantage (in natural environments)
How does the intensity of simple diffusion differ in relation to the concentration gradient of the moved substance? The higher the concentration gradient of a substance the ext
Explain the Decolourizing Agent - Stain Technique? 95% ethanol is used as a decolourizing agent. It has two functions - (1) It acts as protein - dehydrating agent, and (2
Primary producers - Biotic Components The major primary producers of aquatic ecosystems (freshwater and marine) are various species of algae. In terrestrial ecosystems the ma
Determine Pull-ups test for check the body strength? This test is also done to measure upper body strength or endurance by maximum number of pull-ups completed. Subject hangs f
Concept of Production - Ecosystems The ecosystems are unable to function, unless there is a constant input of energy from an external source that is sun. Solar energy enters t
Epidemiology: This infection, although mostly occurring in cows, sometimes also occurs in buffaloes. Under natural conditions, the infection takes place through inoculation by the
Enzymes work to speed up a chemical reaction by: a. attaching coenzymes to the substrate b. heating up the substrate c. lowering the activation energy of the reaction d. supplyi
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