Table 1. Calculation of Maturation Index Ratios for the numerical determination of cellularity in the bone marrow.

Maturation Index Ratio	Definition
M:E	Number of myeloid cells/Number of nucleated erythroid cells
I:M	Number of myeloblasts + promyelocytes + myelocytes/Number of metamyelocytes + bands + segmented
I:Mg	Number of myeloblasts + promyelocytes + neutrophilic myelocytes/Number of neutrophilic metamyelocytes, bands and segmented neutrophils
MMI (1/I:Mg)	Number of neutrophilic metamyelocytes, bands and segmented neutrophils/Number of myeloblasts + promyelocytes + neutrophilic myelocytes
I:Me	Number of proerythroblasts + basophilic erythroblasts/Number of polychromatic and orthochromatic erythroblasts
EMI (1/I:Me)	Number of polychromatic and orthochromatic erythroblasts/Number of proerythroblasts + basophilic erythroblasts

M indicates myeloid; E, erythroid; I, immature; M, mature; I:Mg, immature: mature (granulopoiesis); MMI, myeloid maturation index; I:Me, immature: mature (erythropoiesis); EMI, erythroid maturation index.