Adherent erythroblasts in cocultures have slightly delayed enucleation compared with nonadherent and control erythroblasts. Differential counts of control (■), nonadherent (▩), and adherent (▒) erythroblasts (EBs) were determined as percentages of total erythroid cell elements (erythroblasts + reticulocytes + extruded nuclei) in cultures as described under “Assessment of differentiation and enucleation.” Counts were made with (A) 44-hour cultures and (B) 72-hour cultures. Results are means plus or minus SE from 7 separate experiments; decreased enucleation of adherent erythroblasts was significant at 44 hours (*P < .001), but not at 72 hours (P = .4).