Testicular relapse in acute lymphoblastic leukaemia: studies with an experimental mouse model.

Neither testis nor epididymis was found to be invaded by L1210 leukaemic cells in spite of widespread dissemination through other organs and tissues. The same applied to animals in relapse after protracted remissions induced by cyclophosphamide. Prior damage to the gonadal vascular endothelium by Cd++ did enable leukaemic cells to enter the testicular interstitium, but not the depleted seminiferous tubules. Injection of cells into the lymphatic sinus system of the testis led to rapid peritubular proliferation and systemic dissemination but the seminiferous tubules were not penetrated. The histological appearance resembled that of human ALL. The results suggest that the L1210 system, using the intratesticular route for inoculation can be used to examine the susceptibility to drugs of leukaemic cells in this environment. The potential of drugs to damage the vascular endothelium of the gonad and perhaps contribute to the development of testicular relapse could be assessed following intramuscular inoculation of cells.