Thymic lobes stained for CD11c expression.

WT or PU.1^−/−embryos or cultured thymic lobes were fixed, and cryosections were prepared. Individual sections were stained with αCD11c antibodies followed by an APC secondary antibody. A substrate kit (Vector Black, Vector) was used for visualization. All staining was done in concert to allow relative staining intensities to be compared. No counterstain was used. E14.5 and E16.5 indicate the gestational age of the embryo. FTOC indicates E16.5 thymic lobes that have been placed in organ culture for an additional 10 days prior to sectioning.