¡iErythroid series¡j

¡· Red blood cells take approximately one week to develop from proerythroblasts to reticulocytes. The reticulocytes spend approximately 1¡V2 days in the bone marrow and enter the blood as reticulocytes where they circulate for 1 day before maturing into erythrocytes.

    Examine the reticulocytes noting their color (pink to pinkish grey) and size (approximately 7 £gm). With the Wright stain used in this preparation, they look like red blood cells. Supravital stains (methylene blue or cresyl blue), which stain the polyribosomes in the reticulocytes, can be used to distinguish reticulocytes from mature red blood cells.

    Now pick out orthochromatic erythroblasts. These are approximately the same size (7-10 £gm) and color as reticulocytes but contain eccentrically located small dense pyknotic nuclei. With the electron microscope one sees a condensed nucleus, ribosomes, mitochondria and siderosomes.

    After becoming quite familiar with these cells, pick out polychromatophilic erythroblasts. These contain larger nuclei and a bluish-grey cytoplasm. This cell varies in size (8 to 14 £gm) and the nucleus contains coarse irregularly condensed chromatin masses. Clear patches or scalloped areas may appearust inside the nuclear membrane.

    Next find a basophilic erythroblast (10 to 15 £gm). In this stage of development the cytoplasm is dark blue. The nucleus with moderately clumped chromatin occupies approximately 50¡V70% of the cell. Nucleoli cannot be seen.

    The earliest recognizable cell of the erythroid series is the proerythroblast. This is the largest cell of the series (14 to 18 £gm), containing a deep royal blue cytoplasm with a large centrally located reddish (magenta) nucleus. The chromatin is reticulated and very delicate and contains 2 or more nucleoli, which may stain light blue. This cell may show a reversal of staining pattern in that the cytoplasm may appear darker than the nucleus. Re-examine the cells of the erythroid series, this time beginning with the early stages and note the changes in the relative size and staining characteristics of the cell, the nucleus, and the cytoplasm as development proceeds. Note changes in nuclear-cytoplasmic ratio. If these differences are not apparent to you, sketches may be helpful.

¡´ Proerythroblast

¡´ Basophilic Erythroblast

¡´ Polychromatophilic Erythroblast

¡´ Normoblast (orthochromatic erythroblasts)

¡´ Reticulocyte (polychromatophilic erythrocyte)

¡´ Mature Erythrocyte

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