The effects on bone marrow cellularity and morphology of 6 days' treatment
with granulocyte colony-stimulating factor (G-CSF) in 35 patients were stud
ied. Examination of trephine biopsies showed a highly significant increase
in cellularity (P < 10(-13)). Assessment of aspirates revealed an increase
in the myeloid to erythroid (M : E) ratio (P = 0.00006), the proportion of
myeloid cells (P < 10(-8)), myelocytes (P = 0.00007), metamyelocytes (P = 0
.04), band forms (P = 0.0005) and neutrophils (P = 0.02). This study presen
ts a comprehensive analysis of the effects of six days' administration of G
-CSF on human bone marrow.