Experimental brain tumors and edema in rats. I. Histology and cytology of tumors.

In this study an experimental intracerebral tumor has been investigated with special consideration of structures, which may be involved in edema production and/or resolution. For this purpose a cloned tumor cell line (RG1 2.2) has been injected stereotactically into the brain of BD-IX rats. The tumor has some characteristics in common with low differentiated oligodendroglioma in men. A honeycomb architecture may be seen in the center of the tumor. It is built up by rounded or elongated cells, which can be impregnated in parts. In the central area, cells exhibit a voluminous digestive apparatus, composed of dictyosomes, vesicles, and some vacuoles with a membranaceous or homogeneous content. Tumor cells in the periphery show large processes and a small digestive apparatus. The sinusoidal tumor vessels are composed of an endothelium with many vesicles but no openings.