136 The Lymphocyte and Lymphocytic Tissue 



duct of rats exposed to 750 r of total body irradiation. 4 "' The transient rise 

 occurred from 5 to 7 hours after irradiation. In one patient with total 

 body irradiation of 87.5 r in eight daily treatments, a suggestive abortive 

 rise was observed from 17 to 30 days after therapy followed by a secondary 

 decrease (Fig. 10- ll). 4 " 



Lymphoid Tissue. In lymphoid tissue abortive recovery is characterized 

 by a transient increase in mitoses following the initial inhibition. Barrow 

 and Tullis 1 described a temporary return of mitotic activity in the white 



3000- 



2000- 



I000-! 



MAN 



0-*— r 



8 12 16 20 24 28 32 36 40 44 48 52 



DAYS AFTER IRRADIATION 



Fig. 10-11. Effects of total body irradiation with a total of 87.5 r in 9 days on the blood 

 lymphocyte count in one man. (Data from Nickson. 40 ) 



pulp of the spleen 10 to 36 hours after irradiation of mice with 1000 r. 

 A similar wave of regeneration has been described in myeloid tissue by 

 Bloom. 6 Actual counts of mitotic figures were done by Knowlton and 

 Hempelmann who observed an abortive rise in the number of mitoses in the 

 adrenal gland and jejunal mucosa but not of the lymphoid tissue, possibly 

 due to insufficiently close time intervals. 28 In spite of the difficulties of 

 estimating the number of mitoses and in spite of the resulting paucity of 

 reports, it seems that lymphoid tissue undergoes abortive regeneration. 



In the spleens showing abortive regeneration, Barrow and Tullis observed 

 many abnormal mitosis, such as tripolar and multipolar figures, and lagging 



