Photomicrograph of bone marrow in a patient with pernicious anemia. (A) Megaloblastic change in the nucleus of an erythroid precursors consisting of variegated finely granular chromatin (“salt-and-pepper” appearance) in contrast to the ground-glass texture of normal proerythroblasts. With progressive maturation, chromatin condensation occurs at a slower pace than normal, giving rise to darker aggregates that fuse nonhomogeneously and impart to the nucleus a characteristic latticelike appearance. Undisturbed maturation of the cytoplasm as hemoglobin forms in a cell with an immature-appearing nucleus results in cells that are conspicuous for their lack of synchrony between nuclear and cytoplasmic development. (B) A megaloblastic (“giant”) granulocyte precursor. Original magnification ×100; Wright-Giemsa stain.