blastoderm


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Related to blastoderm: blastodisc, area pellucida, Hensen's node

blastoderm

 [blas´to-derm]
a disk of cells lying betwen the yolk sac and the amniotic cavity, from which the embryo develops.

blas·to·derm

, blastoderma (blas'tō-derm, -tō-der'ma),
The thin, disc-shaped cell mass of a young embryo and its extraembryonic extensions over the surface of the yolk; when fully formed, all three primary germ layers (ectoderm, endoderm, and mesoderm) are present.
[blasto- + G. derma, skin]

blastoderm

/blas·to·derm/ (-derm) the single layer of cells forming the wall of the blastula, or the cellular cap above the floor of segmented yolk in the discoblastula of telolecithal eggs.blastoder´malblastoder´mic

blastoderm

(blăs′tə-dûrm′)
n.
1. The layer of cells that develops on the surface of the yolk in an avian or reptilian egg and gives rise to the germinal disk from which the embryo develops.
2. The layer of cells formed by the cleavage of a fertilized mammalian egg. It later divides into the three germ layers from which the embryo develops.

blas′to·der·mat′ic (-dər-măt′ĭk), blas′to·der′mic adj.

blastoderm

[blas′tədurm′]
Etymology: Gk, blastos + derma, skin
the layer of cells forming the wall of the blastocyst in mammals and the blastula in lower animals during the early stages of embryonic development. It is produced by the cleavage of the fertilized ovum and gives rise to the primary germ layers, the ectoderm, mesoderm, and endoderm, from which the embryo and all of its membranes are derived. Kinds of blastoderm are bilaminar blastoderm, embryonic blastoderm, extraembryonic blastoderm, and trilaminar blastoderm. Also called germinal membrane. blastodermal, blastodermic, adj.

blastoderm

A superficial layer of a fertilised egg which, in birds, is a flat disc of cells at one pole, and in insects, an outer layer of cells surrounding the yolk mass. In eggs with a large amount of yolk, cell division (cleavage) may restricted to blastoderm (meroblastic cleavage).

blas·to·derm

, blastoderma (blas'tō-dĕrm, -dĕr'mă)
The thin, disc-shaped cell mass of young embryos (e.g., reptiles, birds), and its extraembryonic extensions over the surface of the yolk; when fully formed, all three primary germ layers (ectoderm, endoderm, and mesoderm) are present.
Synonym(s): germ membrane, germinal membrane.
[blasto- + G. derma, skin]

blastoderm

the layer of cells formed by cleavage of the fertilized egg in the presence of large amounts of yolk, e.g. in birds, so that the blastoderm forms on one side of the yolk mass, initially as a small blastodisc.

blastoderm

the layer of cells forming the wall of the blastula.
References in periodicals archive ?
Effects of egg collection and pre-incubation treatment on blastoderm development and embryonic mortality in ostrich embryos.
2003) or injection of retrovirus into the blastoderm (Harvey et al.
2003), and following blastoderm injection of retrovirus, approximately 30% of the embryos successfully hatch (Harvey et al.
In later blastoderm stage embryos, MAPK expression is found in just two posterior cells; it fades while, with the onset of epiboly, an outer MAPK positive ring of cells begins to form.
In the second session, images were collected at 7-min intervals, from blastoderm formation to the onset of epiboly, 26-27.
Formation of this important layer involves the collapse of blastomeres at the boundary between the developing blastoderm and the yolk cell cytoplasm.
In the terrestrial chelicerates, spiders and scorpions, most of the cleavage nuclei participate in blastoderm formation.
When in vitro fertilized embryos are cultured in glassware or plastic petri dishes, their development is typically arrested at the early blastoderm stage (<48 h).
Surprisingly, most of the embryos from all treatment groups continue to develop and at 48 h appeared fairly normal, although they often possessed clumps of large cells, uneven blastoderm yolk boarders, and regions where cell layers appeared thicker than controls.
Many lower insects make much or all of their segment pattern after cellularization - a point made particularly clear by recent studies of the grasshopper, Schistocera, which show that the blastoderm becomes cellular even before the aggregation of cells to form the embryonic primordium (2).
heteroclitus occurs by the ingression of superficial deep cells at the margin of the blastoderm during early epiboly (stage 13-[13.