embryonic disc


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Related to embryonic disc: embryonic disk, germ disc

em·bry·on·ic disc

a flattened, almost circular bilaminar plate of cells derived from the embryoblast in the second week of human development.

em·bry·on·ic disc

(em-brē-onik disk)
Flattened, almost circular bilaminar plate of cells derived from the embryoblast in the second week of human development.
References in periodicals archive ?
The twins are monozygotic and do not complete division of the embryonic disc at gestational days 13-15.
Spencer (2003) reviewed approximately 1000 cases of conjoined human twins, including 305 parapagus, and postulated that all conjoined twins arise from two separate notochords (i.e., forerunner of vertebral column) on two originally separate embryonic discs. An alternative theory suggests monozygotic conjoined twins occur when splitting of the embryo is incomplete at the primitive streak stage of development (Kaufman, 2004).
All conjoined twinning, symmetric or asymmetric, is thought to derive from "fusion" of two separate monozygotic embryonic discs but unlikely derived from an incomplete "fission" of the blastocyst [7].