The purpose of Blood Smears Stained with Wright's Stain is to describe the elements seen in blood smears. There are three elements: white cells, red cells, and platelets. Each one is important and one is not less important than the other two. The red cell descriptions are included in two other programs in the series and will not be mentioned here. Platelets will be briefly described, but the major part of this program will be the description of white cells in normal blood and the abnormal white cells that denote acquired, genetic, or metabolic defects. Young cells that are normally limited to the bone marrow will be described in other programs in this series.
Cells are like people - no two look exactly alike. It would be easy to learn morphology if one monocyte was the exact duplicate of another monocyte. There are family characteristics in the different cell lines, but there is much variation between individual cells. It takes time and experience to identify all the cells in the blood and bone marrow and any laboratorians who believe they recognize 100% of the cells are only fooling themselves. It is comforting to know, however, that we can make a diagnosis on a bone marrow even if we can't identify every cell we see.
There are several criteria that are used for identifying cells, one of which is granules. There are two classes of granules in white blood cells that are called specific and nonspecific or azurophilic. Granulocytes are identified by their specific granules, of which there are three types, depending upon their staining characteristics. These are neutrophilic, eosinophilic, and basophilic. Nonspecific granules or azurophilic (so-called because they stain with blue aniline dyes) stain reddish. In normal blood they are present in Iymphocytes and monocytes.
The next four slides and an additional six slides later in the program are for cell identification.
Course Section: 03. Blood Smears Stained with Wright's Stain
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