One example, to be reported in future publications, the host organism lacking the Tspo gene can be supplied with wildtype bone marrow yielding microglia precursors (neo-microglia) that can be identified through their TSPO expression and followed in brain tissue where their interactions with glioma cells can be studied with great clarity both at the histological level and by in vivo imaging. The gene discussed is TSPO; the disease is central nervous system cancer.