Role of class 1 PI3Ks in supporting thymic architecture and cellularity. Representative micrographs depicting thymus size and hematoxylin and eosin-stained sections from WT control (i,iv) and p110γδ^-/- (ii,v) mice and from p110γδ^-/- animals reconstituted with WT fetal liver cells (iii,vi). Delineation of the thymic medulla in these animals (vii-ix) was performed by immunoperoxidase detection of Keratin5⁺ epithelial cells counterstained with Meyer hematoxylin. Cortical and medullary regions in the thymus of p110γδ^-/- mice are indistinguishable, unlike those of WT and reconstituted animals. (Objective, magnification 40 × 4 ×/numerical aperture [NA] 0.16) in panels iv to vi (scale bar, 500 μm) and 200 × (objective, 20 ×/0.7 NA) in panels vii to ix (scale bar, 100 μm). TC indicates thymic cortex; TM, thymic medulla. Data are representative of at least 3 animals for each genotype depicted.