Gross and microscopic examination of Jak3−/− mice. (A) Anatomy of spleens from wild-type (top), +/− (middle), and −/− (bottom) mice. (B) Hematoxylin and eosin (H & E) stain of spleen. Open arrow denotes expanded population of cells surrounding central artery. Closed arrow denotes lymphocytes scattered amongst red pulp (original magnification [OM] × 360). (C) H & E stain of Jak3−/− liver, showing portal infiltrates (OM × 360). (D) H & E stain of lung. Closed arrow denotes infiltrate around large vessels (OM × 360). (E) H & E stain of kidney. Open arrow identifies large vessel infiltrates. Closed arrow denotes emigrating lymphocytes (OM × 720). (F through I) Wright stain of peripheral blood, showing large cells of myelo/premonocytic lineage (OM × 1,080). (J and K) Wright stain of bone marrow smear (OM × 1,080).