Epithelial cell Information and Courses from MediaLab, Inc.

In the center of this picture, there is one large epithelial cell. There are three white cells in a line below the epithelial cell. Many gram positive cocci can be seen. Notice they are primarily in chains.

View control smears under oil immersion. If the control smears stained correctly, read the remainder of the smears.Look at the direct smear macroscopically to locate the stained area.Examine the direct smear under oil immersion and find an area that is properly decolorized.Examine at least ten fields in an area that is properly decolorized.Identify the following nonbacterial cell types: epithelial cells, white blood cells, red blood cells, yeast and hyphae.Look for microorganisms and record their characteristics.Quantitate each type of element found and record on the work card.Interpret the direct smear result.Report the direct smear finding.

Epithelial cells in large numbers within sputum smears means that the specimen is predominantly oral saliva, rather than true sputum from the lung. Epithelial cells in urine smears indicate that the sample has been contaminated by organisms found on the vulva or distal urethra. Bacteria found near or on epithelial cells are usually normal contaminating bacterial flora.White blood cells indicate inflammation and possible infection. The direct smear examination should focus within and around these cells.Red blood cells in a direct smear are not usually significant.Yeast may be present as normal flora in upper respiratory tract or genital tract. They may be significant if they predominate, or if budding yeast forms are seen.Hyphae are more likely to indicate the presence of fungal infection, but this determination requires correlation with clinical findings.Bacteria found in spinal fluid, blood, tissue and specimens from other sterile sites are always significant.Body fluids which are normally sterile must be examined carefully. If only one organism per oil immersion field is identified, then there are about 105 organisms per mL present in the sample! Bacteria observed in specimens from the throat, genital tract and other areas containing normal flora suggest infection only if their composition and type varies significantly from the norm.

A structure which may be misidentified as a cast is a squamous epithelial cell rolled into a cigar shaped cylinder. Unless the nucleus is plainly visible, this epithelial cell may be difficult to differentiate from a cast. A mixed cast contains two or more cell types.

The sediment may be examined using both brightfield and phase-contrast microscopy. With the brightfield microscope, subdued light must be used. Some structures will be missed if there is too much light in the field. Fine focus throughout the examination to identify structures in different focal planes. Scan the slide on low power for quantification of casts, crystals and elements that are present in only a few fields. Use high power to identify casts and count red blood cells, white blood cells and epithelial cells.

Increased numbers of cuboidal cells are found in renal transplant rejection, acute tubular necrosis (diuretic phase), injuries that interrupt blood flow to the kidney, and acute glomerulonephritis accompanied by tubular damage. Ingestion of various drugs and chemicals may cause significant tubular shedding of these epithelial cells. Cuboidal cells are easily seen in urine in cases of salicylate intoxication.

The most common type of cell seen in the urine sediment is the epithelial cell. This slide shows squamous epithelial cells under low power brightfield microscopy. They appear as large flattened cells with abundant cytoplasm and small round central nucleus. Although squamous epithelial cells have little clinical significance they must be differentiated from other cellular elements.

Sometimes epithelial cells appear in groups rather than singly. This field shows a cluster of squamous epithelial cells.

Cells which may be present in the urine include epithelial cells, white blood cells (WBC) and red blood cells (RBC). The epithelial cells in the urine may originate from any site in the genitourinary tract. It is normal to find a few epithelial cells in the sediment. White blood cells may enter the urinary tract anywhere from the glomerulus to the urethra. The WBCs are mostly neutrophils. Red blood cells may originate in any part of the urinary tract. Normally, RBCs do not appear in the urine, although the presence of a few RBCs is not considered abnormal.

Next the number of RBCs, WBCs, epithelial cells, parasites, and fat will be counted. Move to the center of the coverslip and examine 10 fields under high power (40x) brightfield. Use phase-contrast as needed. Determine the average number of each element found and record the findings as number per high power field (#/HPF). An abundance of any one element may be recorded as >100/HPF when 1/4 field is counted and the total field is estimated to be greater than 200/HPF.

The Sternheimer-Malbin (SM) stain is a commonly used supravital stain containing crystal-violet and safranin. WBC's, epithelial cells, and casts stain well with SM stain. Sedi-Strain (Clay Adams, Sparks, MD) and Kova stain (ICL Scientific) are among those commercially available. Nuclei and cytoplasm of various cells can be stained with a 0.5% solution of toludine blue.

Oval fat bodies are degenerating tubular epithelial cells filled that contain refractile fat droplets. These fats have been absorbed by the tubular cells after being leaked through abnormal glomeruli. They appear as grape-like clusters of variable size and are highly refractile.