Peripheral blood smears in disorders of the erythrocyte membrane. A. Hereditary spherocytosis. Characteristic spherocytes lacking central pallor are seen. B. Hereditary elliptocytosis. Smooth, cigar-shaped elliptocytes are seen. C. Hereditary pyropoikilocytosis. Pronounced microcytosis, poikilocytosis, fragmentation of erythrocytes and elliptocytes are seen. D. Hereditary stomatocytosis. Erythrocytes with slit-like, stomata are seen. Reprinted with permission from Gallagher PG. Disorders of erythrocyte metabolism and shape. In Hematologic Problems in the Neonate. Christensen RD (ed). WB Saunders, Philadelphia, 1999.