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Lesson 4-1 . General Information


In this lesson, all normal and most commonly seen abnormal blood cells are morphologically described. Although general rules for identification are given along with representative photographs and drawings, it is important to realize that no biological entity fits the guidelines precisely.

The present classification of blood cells is manís attempt at identifying stages of maturation by assigning artificial steps to a continuing process. The process is a smooth, continuing one, and therefore no one cell ever precisely fits the criteria for a specific stage. These stages are artificial classifications that exist to simplify identification.


Certain general rules are applied to all cell maturation (hemopoiesis) either in the erythrocyte, leukocyte, thrombocyte, or plasmocyte series. Although these rules are broken by individual cells, they are an aid to classifying cells.

  • Immature cells are larger than mature cells and become smaller as they mature.
  • The relative and absolute size of the nucleus decreases as the cell matures. In some cell series the nucleus disappears.
  • The cytoplasm in an immature cell is quite blue in color and lightens as the cell matures.
  • The young nucleus is reddish and becomes bluer as the cell ages.
  • Nuclear chromatin is fine and lacy (lacelike) in the immature cell It becomes coarse and clumped in the more mature cells.

If there is doubt in the identity of a cell, classify to the more mature form.


David L. Heiserman, Editor

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Revised: June 06, 2015