Biopsy evaluation of thymus allografts shows thymopoiesis. Subject 1 (A-B) and subject 2 (C-D). Cytokeratin reactivity (A,C) and CD3 reactivity (B,D). Scale bar, 50 μm. The microscope was an Olympus VANOX AHBS3. The magnification was 40× using a 40× numerical aperture objective lens (Olympus SPLAN 40×). The photomicrograph was taken at room temperature. Neither imaging media nor fluorochromes were used. The camera used was an Olympus DP70 digital imaging camera. Acquisition software was Olympus DP Controller. Subsequently, Adobe Photoshop 6.0 was used to compose this figure.