Quantitative Measurement of Hematopoietic Cells

In recent years with the availability of more accurate methods, attention has been directed towards the quantitative aspects of both erythropoiesis and leukopoiesis. It has been difficult to measure the precursor cells in the marrow, and their exact number still remains in question. Previous estimates of total marrow cells have utilized three general methods of approach: a) direct measurements of volume and cellularity of marrow in animals (1); b) calculations based on an assumed maturation time and on the known life span of the erythrocyte (2); and c) calculation based on the frequency and the estimated duration of marrow mitosis (3). The first of these methods imposes formidable technical difficulties and cannot be performed in man; the other two involve assumptions not subject to validation. The present report concerns a direct technique in which the various procedures and assumptions employed are scrutinized. The method employs the eythroid tag Fe59 to relate the cells in an aliquot of marrow to the total marrow, as originally proposed by Suit (4).