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!
Gastrulation
The end of cleavage of the unicellular zygote results in the creation of multicellular blastula, which may be a solid structure with no a cavity (stereoblastula), or its cells might be arranged in the form of a one cell or several cells thick epithelium around a cavity (coeloblastula) or around or on yolk's top (Superficial blastula, Discoblastula). In either case the blastula has no similarity to the shape or organization of the body. Hence, by the consequent developmental stage the simple blastula should change itself into a more complex embryonic structure (gastrula) upon that the adult like body may be built up. Such type of a process of transformation is termed as gastrulation. It is a very important phase of ontogenetic development that marks the beginning of the development of form and organization of adult body. In the metazoans (apart from in sponges and coelenterates), the various tissues and organs of the body develop from cells that become arranged in the form of three layers, the outer ectoderm, the inner endoderm and the mesoderm among these two layers.
The three layers are termed as the germinal layers. With the exception of some parasitic flatworms a new cavity that is termed as the archenteron (future alimentary canal) is formed surrounded via endoderm. In the blastula all the cells are situated on the surface forming the blastoderm. During gastrulation there takes place displacement of the parts of blastoderm that is why the presumptive endodermal and mesodermal cells are removed from the surface of blastula and brought into the interior of embryo in which the respective organs are made in the course of further development. The cells of the presumptive ectoderm remain on the surface. So, the single layer of cells, the blastoderm, gives rise to three germinal layers viz. ectoderm, mesoderm and endoderm. Hence, gastrulation is a dynamic process involving large scale movement of blastula cells resultant in their arrangement in a way that establishes the basic body plan as per to which the embryo has to develop further. As these movements lay the foundation of the form and organization of the body they are called morphogenetic movements. They include movements of epithelial layers of cells as whole as well as independent movements of cells that break loose from epithelium and become mesenchymal.
What are the disadvantages of protozoa
Fl u o r osi s Continual ingestion of small amount of fluoride through feed or water leads to fluorosis in animals. The toxic effects are based on amount of fluorine inges
Mrs. M is a 35-year-old Hispanic female with no known past medical history; does not have a primary care provider (PCP). She presents to the emergency department with the following
Medical Management In chronic renal failure there is irreversible renal failure. The goals of medical management are: To promote maximal renal function To ma
Which of the below is usually referred to as "master gland" because it regulates so many body activities? Is it: a) Pituitary gland b) Thyroid gland c) Adrenal gland d
GOLGI APPARATUS It is a complex cyctoplasmic structure made up of smooth membrane saccules or cisternae, a network of tubules with vessicles and vacuoles, which take part i
how to determine that the phenotype of a wild type is due to the action of one or two genes?
Results : Pericardiectomy used to have a mortality of 10-15 per cent in the earlier era. At present it is around 3 to 5 per cent and does not approach 0 per cent even though it
What is the secondary structure of a protein? The secondary protein structure is formed by the manner its amino acids interact by the intermolecular bond. These interactions ma
If the osmolarity of plasma (inside a capillary) is 300 mOsM, the osmolarity of the tissue fluid (interstial fluid) is 400, and the membranes are permeable to water but not to salt
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: +1-415-670-9521
Phone: +1-415-670-9521
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd