Scanning EM and cytospins of nascent reticulocytes before and after filtration. All cells had been cultured following protocol A. (A) Scanning electron microscopy image of day 18 reticulocytes pre-filtration. The arrowheads indicate free nuclei and/or enucleating cells (i). The panel on the right shows an enucleating reticulocyte (ii). (B) Scanning electron microscopy images of leukocyte filtered reticulocytes (i,ii,iv) and adult peripheral blood (iii). Arrows indicate some of the more mature reticulocytes. Panels ii and iv depict an R2 reticulocyte and an almost mature RBC, respectively. (C) Cytospin image of unfiltered (i) and leukocyte-filtered (ii) day 20 reticulocytes. Scale bar indicates 20 μm.