'3H-testosterone distribution and binding in rat thymus cells in vivo'.

Autoradiography and biochemical investigations showed that [3H]-testosterone where injected intraperitoneally into male white rats was incorporated rapidly into thymus lymphocytes. Thymic cortex contained more silver grains than medulla, and larger lymphocytes were more labelled than medium or small lymphocytes. Cytosol fraction of thymus cells labelled in vivo with [3H]-testosterone, contained the largest quantity of labelled hormone. A 4S cytosol fraction binds [3H]-testosterone. This could be separated by Sephadex chromatography or by linear sucrose gradient centrifugation. Nuclear extract contained also a small quantity of the labelled hormone.