HUMAN TOLERANCE TO THERMAL NEUTRONS 



449 





Fig. 3. Whole brain section of case 8180 r showing a neoplasm producing enlarge- 

 ment of the occipital lobe and demyelinization of the adjacent area. The opposite 

 occipital lobe and the whole cerebellimi are intact. 



the tip of the frontal lobe and shows part of the scar viewed in Fig. 5. In 

 Fig. 7 the photomicrograph shows a section from the scar seen in Fig. 6 and 

 is from the outer surface of the brain. The connectixe tissue reaction with 

 fibrocytes and the glial reaction are both predominant. Of great importance 

 is the fact that within the effective depth no residual neoplastic cells are 

 obser\ed in this region. 



Figure 8 shows a photomicrograph from the region about 3 cm deep to the 

 gross area of scarring. The neurons are intact, and there is no destructive 

 effect of the thermal neutrons in the non-neoplastic area adjacent to the site 

 of the previous primary neoplasm. Figure 9 is taken from the meninges at the 

 site of the arrow seen in Fig. 6 and within the port of irradiation. The 

 meninges are not thickened, although occasionally phaoocytic cells with 

 blood pigment arc present. In general, this is a mild reaction, and there is no 

 evidence of fibrosis from irradiation. Just below this area, Fig. 10 (a high 



