Development of subrenal capsule tumours following transplantation of rat RN6 multicell spheroids.

We describe here the growth rate, morphology and ultrastructure of the RN6 neurinoma spheroids in culture and after syngeneic transplantation under the renal capsule of adult BDIX rats, where sequential growth and tumour angiogenesis studies were performed. The tumour cells in solid avascular multicell spheroids (MTS) and in subrenal capsule tumours (SCT) showed similar morphology and ultrastructure. The vascularization of spheroids started 2 to 3 days after implantation under the renal capsule from proliferating venule-like vessels of the kidney parenchyma. The MTS were soon densely penetrated by hairpin loops of newly formed capillaries. Such vascularized spheroids grew rapidly. The morphology, ultrastructure and permeability characteristics of newly formed tumour vessels and their relationship to the development of tumour necrosis are described. This syngeneic model of subrenal capsule transplantation of neurogenic tumour spheroids appears to be useful for studies of the mechanisms of tumour angiogenesis, tumour necroses and the host response to malignant tumours of the nervous system.