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Spot in yolk of egg where segmentation begins.

see cicatricle

The term is, also, applied to a small white spot, called the tread, chal'aza, chala'zium, observable at the surface of a fecundated egg. See Molecule.

The germinating point in the embryo of a seed or in the yolk of a fecundated ovum, called the "tread" from its resemblance to a scar. See archiblast. [Lat.]

[L.] The point of germination in an egg.

[L.] The same as the scar, in a seed.