the early stage of an embryo after the first cleavages of the ovum; also, the layer of cells of which the early embryo is composed;
the early embryo developing from a blastodisc, after the blastocoel has formed.
in an insect embryo, the layer of cells that surrounds the internal mass of the yolk.
a layer of cells on the inside of the blastula
The layer of cells formed by cleavage of the fertilized egg in the presence of large amounts of yolk
A fertilised true egg.
A fertilized true egg.
Gr. blastos - germ, bud, shoot; Gr. derma - skin]. The divided germinal disc of a megalecithal egg lying on the yolk and composed of three regions: the area pellucida, the area opaca, and the syncytial periblast. Synonym: blastodisc.
In an insect embryo, the layer of cells that completely surrounds an internal mass of yolk.
In an insect embryo, the stage in which there is a single layer of nuclei (syncitial blastoderm) or cells (cellular blastoderm) surrounding the central yolk.
A Blastoderm as of 1935 is the layer of cells formed at one pole of the yolky egg of reptiles and birds. The yolk prevents the division from taking place through the egg. At the pole containing less yolk, the ovum divides and subdivides, forming the blastoderm, which gradually spreads around the yolk and forms the embryo.