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formation of blastopore the slit such as opening of the initial groove is the opening of the developing blastopore and its dorsal rim is termed as
gastrulation in amphibians amphibians comprise a large and moderately telolecithal egg cleavage is holoblastic and unequal generating a spherical
second stage of invaginationthe 2nd stage of invagination starts with release of secondary mesenchyme from the tip of archenteron into the blastocoel
first stage of invagination the large endodermal cells that are remaining in the vegetal plate move laterally towards the centre of the plate and
gastrulation in some animalsas mentioned before gastrulation marks the beginning of morphogenesis that is development of body form and organisation
emboly movement - involution it denotes turning in or rolling over involution of mesodermal blastomeres has been observed in amphioxus reptiles
morphogenetic movements gastrulation is a dynamic process including a variety of coordinated movements of cells of dissimilar areas of the blastula
radioactive labelling radioactive labelling method has been effectively applied on the chick blastoderm the method includes labelling one embryo
vital dye staining in this type of method a piece of agar or cellophane soaked in the solution of a vital dye neutral red nile blue sulphate and
fate maps the details of the procedure of gastrulation are not simple to understand without the knowledge of positions of the cells of the future
features of the gastrulationthe significant features of the gastrulation area proteins of many new types that were not present in the egg or blastula
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
formation of new membranes divisions of the egg or blastomeres raise the total surface area of the two daughter cells to be covered via membrane at
mechanism of cleavage such as the mitotic division in any cell cleavage is the result of two events mitotic nuclear division karyokinesis followed
structure of blastulathe structure of blastula turns into modified in several animal groups the changes are related to the amount of yolk deposited
products of cleavage morula and blastula in several cases the blastomeres in early cleaving stages tend to presume spherical shape like that of the
meroblastic or partial cleavagethe egg does not divide totally because divisions are restricted to only a part of the egg where as the rest of the
bilateral cleavagein some animals for example tunicates and nematodes although in different way the arrangement of 4 blastomeres after second
types of cleavagea radial type if each of the blastomeres of upper tier lies exactly over the corresponding blastomeres of the lower tier the pattern
patters of cleavage in most of the animal groups with spherical or almost spherical egg and little or moderate amount of yolk micro-or mesolecithal
basic planes of cleavage the basic planes along which the egg and its daughter blastomeres are divided during early cleavage area meridional plane -
planes of cleavage the ova of most of the animal groups except some specific cases like insects are spherical or nearly spherical having their own
principles governing cleavage a the nucleus and mitotic achromatic figure tend to occupy the centre of active cytoplasmic density of the dividing
influence of yolk on cleavage though biological significance of yolk is to provide nourishment to the developing embryo it is not part of the active
peculiarities of mitosis - cleavagefrom the following you will learn that the mitosis in the phase of cleavage has some striking peculiaritiesa