proplastid

A small *plastid , less than 1.0 μm in diameter, with rudimentary internal structure. The inner of the two surrounding membranes is often extended into finger-like projections. Small membrane-bound vesicles and a few starch grains and plastoglobuli may be present in the matrix. Proplastids are present in the cells of meristematic tissue and are thought to differentiate into mature plastids.