344 



RADIOISOTOPES IN BIOLOGY AND AGRICULTURE 



activity is more generally distributed than in the case of the older animals. 

 Figure 7-10 presents an autoradiogram of the pyloric region of a 10-day- 

 old rat sacrificed 2 hr after a subcutaneous injection of S^^ (courtesy of 

 L. F. Belanger). There is considerable deposition of radioactivity all 

 over the pyloric gland A . However, there is little or no deposition over 

 Brunner's glands B. Individual spots over the duodenal villi coincide 

 with the position of the mucous goblet cells C. This autoradiogram 



Fig. 7-10. '6^=' autoradiogram (X32) of pyloric region of lO-daj^-old rat at 2 hr after 

 injection. There was considerable deposition over the pyloric gland A. little or no 

 deposition over Brunner's glands B, and slight deposition over mucous goblet cells C. 

 (Courtesy of L. F. Belanger. Inverted coating method.) 



(X32) was prepared by Belanger's inversion modification of the coating 

 method (30). 



Figure 7-11 shows the distribution of C'^ in the roots of corn seedlings 

 after exposure of the plant to an atmosphere of labeled CO2 (38). The 

 greatest amount of radioactivity was found in the terminal millimeter, 

 and it can be seen from Fig. 7-11 that the C^^ was concentrated in the 

 inner cortex A, outer stele B, and the superficial cells C. The path of 

 translocation of the C '''-labeled compounds is probably indicated by the 

 dark areas of the more basipetal portions of the root apex D. In this 

 experiment the plants were grown in a bell jar and, after introduction of 

 about 100 mc C'"*, illuminated for a 24-hr period. The root apices were 

 embedded in paraffin and sectioned longitudinally at 8 to 10 ^ using stand- 

 ard histological techniques. The sections were mounted onto NTB2 

 plates and exposed for 5 to 8 days. After exposure the paraffin was 



