FETAL X-RAY EFFECTS: CEREBRAL CORTEX 



33 



1600 



1400 



1200 



< 800 

 o 



CE 

 O 



o 60d 



400 



I - CONTROL 

 t. = lOOr 

 D = 200r 

 o = 300r 



AGE (DAYS) 



20 



Fig. 5. Comparison of cortical thickness in area 2 in irradiated and control groups 

 in early postnatal period. 



It is particiilaily noteworthy that the cufves illustratin<i the increase in 

 cortical thickness for radiated and control ijroups tend to be parallel. While 

 only the curves for area 2 are illustrated (Fiij. 5). it was observed on plottinti 

 out the \alues for the other areas that the curves for each area are quite 

 characteristic for that area, with the cunes for all radiated and control 

 series showina: the same sjeneral trends. One notable exception to this rule 

 was observed in area 4 in the 200 r series. Here the value for cortical thick- 

 ness in the 200 r jjroup drops below that for the 300 r animals. With this 

 exception, the differences in cortical thickness in area 4, 41, and 17 are of 

 about the same order as in area 2. 



While cortical thickness thus appeared to exhibit an inverse relationship 

 to radiation dose, no marked diflPerences in relati\e thickness of layers were 

 observed in area 2 between irradiated and nonirradiated rats even in the 

 300 r series. No detailed obser\ations other than cortical thickness were made 

 in areas 4, 41, and 17. No a;eneral cytolos^ic differences between neurons in 

 irradiated and control animals were observed in area 2. and no abnormalities 

 of blood vessels were found. It is of course recognized that the latter would 

 not be well demonstrated in Nissl preparations. 



