The total cellularity of the bone marrow in man.

The Fe(59) method of Suit (1957) has been used to estimate total bone marrow cellularity in 10 haematologically normal patients. A mean figure of 10.4 x 10(9) nucleated cells/kg. body weight was obtained. Simultaneous estimates from marrow obtained by rib excision produced a mean value of 11.1 x 10(9) nucleated cells/kg. Previous work by this and other methods is reviewed. While some results agree well with those of the present work, one is higher by 50% and another by 300%. Corrections are suggested which reduce these figures and bring all published results within a small range. Reasonably accurate determinations of total marrow cellularity in disease will not be possible until more is known of marrow Fe(59) uptake in abnormal states.