An undifferentiated embryonic cell.

Very early (immature) cells

A very immature blood cell.

A phase of cell growth that occurs before a blood cell becomes fully mature.

A white blood cell that fails to mature, multiplies rapidly, and crowds out normal blood cells; inhibits the ability of normal cells to effectively defend the body against microorganisms.

An undifferentiated normal cell in an early stage of development; also means a leukemic cell of indeterminable type.

A cell that divides, generally asymmetrically, to give rise to two different progeny cells. One is a blast cell just like the parental cell and the other is a cell that enters a differentiation pathway. In this manner, a continuously propagating cell population can maintain itself and spin off differentiating cells.

early committed marrow precursor of mature red and white cells. This cell accumulates in the marrow in acute leukemia, and may appear in the blood in large numbers.