SOME FACTORS RESPONSIBLE FOR VARIATION IN COUNTING SOMATIC CELLS ON PRESCOTT-BREED SMEARS OF MILK1

Summary By means of direct microscopic observation of cells in stained smears and projection of a series of color transparencies, differences in criteria used by individuals for identification of cells to be counted in Prescott-Breed smears were discovered and described. Extensive studies revealed a unique pattern of cell distribution within smears which can materially affect the outcome of a cell count depending upon the area selected for cell counting. Among other factors, variation in size of the smear was found to have a marked affect upon resultant sample count.