“…In particular, the lack of methods for direct observations of the dynamics of tumour invasion in the nontransparent living host tissue limits developments in this aspect. CT, MRI and in vivo microscopy are useful for the detection of tumours and metastases (Walsh & Goplerud, 1981;Gabbert, 1985;Kim et al, 1990;Bennet et al, 1991;Van Leeuwen et al, 1994, 1995Kan et al, 1995) and for the follow-up of the response to therapy (Tacek et al, 1991;Hricak et al, 1993), but these techniques are based on the acquisition of noninvasive virtual sections with a spatial resolution of the order of millimetres. Therefore, these techniques do not provide sufficient spatial resolution for detection of micrometastases (Schreve et al, 1984) or interactions between cancer cells, stroma and surrounding tissues.…”