Ultrastructural comparison between the parenchymal cells of tumors derived from parent and hybrid lines of C1300 mouse neuroblastoma and C6 rat glioma.

Hybrid cell line 108CC5, obtained by fusion of N18TG2 mouse neuroblastoma and C6BU1 rat glioma lines, was injected intracranially or s.c. into nude mice. The tissues of the resultant intracranial and s.c. tumors were processed for light, phase, and electron microscopy. For comparison, the tumors induced by inoculation of the parent lines in the respective animal hosts were also studied. Histologically, the hybrid tumor resembled a very cellular, anaplastic neo plasm bearing a greater resemblance to the neuroblastoma than to the glioma type of growth. Under the electron micro scope hybrid tumor cells also showed a greater resem blance to neuroblastoma than to glioma tumor cells. Hybrid tumor cells were large (even huge). The cytoplasm con tained all the typical organelles. Dense core vesicles and intracisternal type A particles were a regular feature of these cells. Annulate lamellae were also seen frequently. Some of the large cell processes contained numerous microtubules; others were instead packed with filaments. Dense core vesi cles and clear vesicles were clustered along some of these processes and at their tips. Unequivocal synapses were not seen, but profiles suggestive of these structures were ob served occasionally. Type C virus particles, both budding at the cell surface and lying extracellularly, were commonly noted in the specimens of the hybrid tumor. In conclusion, hybrid tumor cells bore a greater morpho logical resemblance to neuroblastoma than to glioma tumor cells and showed the "differentiated" morphology of neuro