Page 226 - Atlas of Histology with Functional Correlations

FIGURE 6.14 ■ Bone marrow smear: selected precursors of different blood
cells. Stain: Giemsa stain. High magnification or oil immersion.

ERYTHROCYTE DEVELOPMENT

In the erythrocytic cell line, the pluripotential stem cell differentiates into a
proerythroblast (1), a large cell with loose chromatin, one or two nucleoli, and
a basophilic cytoplasm. The proerythroblast (1) divides to produce a smaller cell

called a basophilic erythroblast (2) with a rim of basophilic cytoplasm and a
more condensed nucleus without visible nucleoli. In the next stage, a smaller cell
called the polychromatophilic erythroblast (3) is produced. These cells show a
decrease in basophilic ribosomes and an increase in the acidophilic hemoglobin

content of their cytoplasm. As a result, staining these cells produces several
colors in their cytoplasm. As differentiation continues, there is a further
reduction of the cell size, condensation of nuclear material, and a more uniform
eosinophilic cytoplasm. At this stage, the cell is called an orthochromatophilic

erythroblast (normoblast) (4). After extruding its nucleus, the
orthochromatophilic erythroblast (4) becomes a reticulocyte (5) because a small
number of ribosomes can be stained in its cytoplasm. After losing the ribosomes,

225