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White cells are less refractile and appear somewhat granular in appearance. In general, white cells will be larger than red cells. The segmented nucleus in neutrophils can be seen on high power. Lymphocytes and monocytes may be more difficult to differentiate in an undiluted, unstained specimen.Cells are counted in the four corner squares and the center square on both sides of the hemacytometer. The number of cells counted equals the number of cells/microliter.The ruled area of one side of a hemacytometer is shown on the right, with routine counting squares for red and white cell counts. Each large square is 1 mm wide by 0.1 mm in depth. The area for counting an undiluted specimen is 10 square millimeters, or 5 large squares on each side.

The chromatin pattern of the basophil nucleus is not quite as coarse as that of the neutrophil or eosinophil nuclei. Although the nucleus is usually segmented, the lobes are often difficult to discern because they tend to crowd together and are obscured by the cytoplasmic granules.

Any cell containing specific granules in which the lobes of the nucleus are connected by a filament is considered a segmented cell.A filament is defined as a thread-like structure.Since at times, in viewing a three dimensional object from one direction it is impossible to be certain whether two parts of the nucleus are connected by a filament or band, it is suggested that such cells always be placed in the segmented category, since this is the more differentiated and more common cell.

Neutrophils have a relatively short life span.They are produced in the bone marrow, and when they reach the band or segmented stages are released into the peripheral blood.They remain there for approximately ten hours before randomly entering body tissues.Neutrophils in the blood stream can be divided into circulating granulocyte pool(CGP) and marginating granulocytic pool (MGP).The white blood cell count reflects the cells in the circulating pool.The cells in the marginating pool move quickly into the circulating pool when needed.During an infection the neutrophil concentration of the peripheral blood can increase almost immediately due to the shift of these cells from the marginating pool and release from the bone marrow storage pool, if needed.Neutrophils then migrate to areas of tissue damage or infection.Neutrophils do not reenter the blood stream from the tissues, thus end their life in the tissues either as a result of phagocytosis or senescence.

White blood cells also stain gram negative and usually have a segmented nucleus. Their average diameter is about 12 microns.

Epithelial cells are larger than white blood cells and red blood cells, and contain a single nucleus. White blood cells (pus cells) usually show a segmented nucleus. Red blood cells are 1/2 to 2/3 as large as white blood cells, contain no nucleus, and are gram negative.Hyphae are gram positive tubular filamentous fungal elements which may show branching or intertwining. Yeast cells are round to oval, often budding, gram positive fungal elements, about the same size as RBCs. They are generally much larger than bacteria.

Waxy casts appear as cylinders of smooth, highly refractive material. They are yellow, homogeneous and their ends may be square or broken off. Cracks may occur within the cast, giving it a segmented appearance. Waxy casts are believed by some to be the final stage of degeneration of the fine granules of granular casts. Since the granules need time to degrade, this finding implies localized nephron obstruction. Waxy casts are seen in chronic renal failure, and acute and chronic renal allograft rejection. Unusually broad waxy casts are known as renal failure casts. These very broad casts are created in the dilated tubules seen in end-stage renal disease.

Another form of renal epithelial cells originates in the collecting ducts and measures 12-20 microns. These are identified by their characteristic cuboidal shape and large usually slightly eccentric nucleus. Cuboidal cells are sometimes confused with neutrophils. Neutrophils, however, are slightly larger to nearly twice as large (20-35 microns) as cuboidal cells and have a segmented or band-shaped nucleus while cuboidal cells have a single round nucleus. This view under high power phase contrast shows two cuboidal cells lying between squamous cells.

Toxic granulation is manifested by the presence of large granules in the cytoplasm of segmented and band neutrophils in the peripheral blood. The color of these granules can range from dark purplish blue to an almost red appearance. Toxic granules are azurophilic granules normally present in early myeloid forms, but which are not normally seen at the band and segmented stages of neutrophil maturation. These granules contain peroxidases and hydrolases. Toxic granulation is seen in cases of severe infection, as a result of denatured proteins in rheumatoid arthritis or, less frequently, as a result of autophagocytosis. Infection is the most frequent cause of toxic granulation. This type of granulation may be seen in cells which also contain Dohle bodies and/or vacuoles. Cells containing toxic granules may have decreased numbers of specific granules. Cells containing only a few specific granules, with or without toxic granules, are said to be degranulated. The nucleus in degranulated cells may often be round-bilobed, smooth and pyknotic. This type of nucleus is the result of aging and will disintegrate soon. Increased basophilia of azurophilic granules simulating toxic granules may occur in normal cells with prolonged staining time or decreased pH of the stain.