-blast Also -blastic.
An immature or embryonic cell.
[Greek blastos, germ or sprout.]
Examples include erythroblast (Greek eruthros, red), an immature erythrocyte, a red blood cell; neuroblast, an embryonic cell from which nerve fibres originate; and fibroblast, a cell in connective tissue which produces collagen and other fibres. Sometimes the ending refers to an abnormality, as in lymphoblast, an abnormal cell resembling a large lymphocyte, produced in large numbers in a form of leukaemia. It can also denote a germ layer of an embryo: epiblast (Greek epi, upon), the outermost layer of an embryo before it differentiates into ectoderm and mesoderm; trophoblast (Greek trophē, nourishment), a layer of tissue on the outside of a mammalian embryo, supplying it with nourishment and later forming the major part of the placenta. A mature cell is indicated by -cyte.
Words such as counterblast or sandblast are compounds of the English word blast.
Forms in -blastic are adjectives (see -ic) that may be derived from nouns in -blast: erythroblastic, lymphoblastic, trophoblastic. They may also denote a thing that has undergone a particular kind of development: poikiloblastic (Greek poikilos, variegated, varied), of the texture of a metamorphic rock in which small crystals of a mineral occur within crystals of its metamorphic product; diploblastic (Greek diplous, double), having a body derived from only two embryonic cell layers (ectoderm and endoderm, but no mesoderm), as in sponges and coelenterates.