Impairment of thymic cellularity and architecture in adult mice double deficient in Fl and Il7r expression. (A) Typical thymuses from 8- to 10-week-old WT, Fl^−/−, Il7r^−/−, and Fl^−/−Il7r^−/− mice. Bar represents 0.5 mm. Photographs taken from Nikon SMZ-U dissection microscope (Melville, NY) with ED plan and 7.5-fold magnification using Sony Digital Hyper HAD color video camera (San Jose, CA) and MicroGraphix (Oxfordshire, United Kingdom) PhotoMagic software. Images were directly transferred to Microsoft PowerPoint (Redmond, WA) and adjusted for size. (B) Typical structure of thymuses from 8- to 10-week-old WT, Fl^−/−, Il7r^−/−, and Fl^−/−Il7r^−/− mice. Bar represents 0.5 mm. Images acquired with fluorescent microscope (Olympus BX51; Tokyo, Japan), with 10× and 20× objectives (Olympus UplanF1 10×/0.30 NA and 20×/0.50 NA, respectively) using Olympus DP70 camera and acquisition software (DP Controller; Olympus Optical, Tokyo, Japan) and analysis software (analySIS; Olympus Soft Imaging Solutions, Münster, Germany). (C) Total thymic cellularities from 8- to 10-week-old WT, Fl^−/−, Il7r^−/−, and Fl^−/−Il7r^−/− mice in log scale. Data represent mean (SD) values of 7 to 8 age-matched mice of each genotype. *P < .01 comparing Il7r^−/− and Fl^−/−Il7r^−/− mice.