EFFECT OF SINGLE AND FRACTIONATED DOSES OF IRRADIATION 



37 



The mitotic injuries shown by the marrow, lead to cell death and account 

 for the depletion of the white cells in the peripheral blood. 



Table II. Percentage of cells with chromosome abnormalities 



f Figures in brackets are number of cells analysed. 



Mitotic index 



The rate of mitosis has been determined in the bone-marrow samples by- 

 analysing 2,000 cells, and coimting the number of cells in prophase and 



0-90 



070 



0-50 



0-30 



0-10 



0-90 



070- 



0-50 



0-30 



0-10 



X I80r 



.<i-d 1^ 



(5W) 



3x|80r 



'-^'■ 



^53 



# 





' 2x|80r 



4x|80r 



m 



(7W) 



n I Day ^6 Days 



Fig. 1. 



Control 



metaphase. The data obtained are given in Fig. 1. The mitotic index, 

 (number of dividing cells x 100) 



(total number of cells counted) 



in 5- and 7-week-old C57BL mice is given as 



