Refractory anemia with ringed sideroblasts (RARS). Bone marrow biopsy specimen (H & E stain). This high power view of the biopsy illustrates the erythroid hyperplasia. The immature cells at the arrows are immature erythroid precursors, which are characterized by a round to oval nucleus with vesicular chromatin pattern, and prominent, often comma-shaped nucleoli, and a modest rim of blue-grey (amphophilic) cytoplasm.