Comparative ultrastructural study of the effects of serum-free medium and dibutyryl-cyclic AMP on newborn rat astroblasts.

Modifications of cell shape induced in cultured newborn rat astroblasts by serum deprivation or dibutyryladenosine 3'-5' monophosphate (dBcAMP) are described. Serum suppression modifies the adhesitivity of the cells to the substrate, but this modification is not consistent with a true differentiation. The main ultrastructural feature of dBcAMP-treated astroblasts is the presence of an extensive system of 90 A microfilaments, while control cells are relatively devoid of these structures.