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 the Regulation of Blood Glucose Concentration? A number of mechanisms function to maintain blood glucose at remarkably constant level of 70-100 mg/dl under fasting cond
Copulation and Fertilisation in Hermaphrodites Copulation between hermaphrodites is common. Flatworms possess a cirrus and penis that is inserted into the uterine vaginal ope
Absolute time is one of the two types of geologic time (relative time being the other), with the distinct age date established generally by the decay of the radioactive elements,
disadv of protozoa
Sporozoans – Protozoan Sporozoans of the genus Plasmodium are responsible for causing a serious human disease, malaria. They are among, the best known parasites which live in
Why are euglenas involved in polemics related to their taxonomic classification? Euglenas are included in taxonomic polemics because they tend to be classified sometimes as pro
Which is the extraembryonic membrane whose function is to store nitrogen wastes of the embryo? Is this function present in placental mammalian embryos? The allantois is the ext
virus symmetry
Which level of a gene, such as the ADH gene and its encoded product should have the highest homology among different species? Explain your answer. A. The genomic DNA sequences o
Which type of reproductive structure has a better chance of survival if there was a sudden temperature change in its environment? A.)asci B.)zygosporangium C.)basidium D.)lichen
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