VAGINAL CYTOLOGY

48 VAGINAL CYTOLOGY



Rick L. Cowell, James H. Meinkoth, Debbie J. Cunningham



1 List the four types of normal vaginal epithelial cells identified on cytology smears.



a. Basal cells

b. Parabasal cells

c. Intermediate cells

d. Superficial cells


2 What are basal cells?


Basal cells are located on the basement membrane and are the precursor cell for the other vaginal epithelial cells (parabasal, intermediate, superficial). Basal cells are seldom observed on vaginal cytology smears and appear as small cells with a small amount of basophilic cytoplasm.



3 What are parabasal cells?


Parabasal cells are the smallest and most immature of the epithelial cells typically observed on cytology smears. They appear as small round cells with a small amount of basophilic cytoplasm and a roundish nucleus. Parabasal cells with cytoplasmic vacuoles are called foam cells.



4 What are intermediate cells?


Intermediate cells are larger than parabasal cells, often being twice as large or larger. Depending on their size, intermediate cells are subclassified into small and large intermediate cells. The size of intermediate cells depends on the amount of their cytoplasm because the nucleus of both large and small intermediate cells is about the same size and typically roundish. The cytoplasm of small intermediate cells is usually smooth and round to slightly oval. The cytoplasm of large intermediate cells tends to be angular and occasionally may also be irregular and folded. The cytoplasm is typically blue to blue-green in both small and large intermediate epithelial cells. The terms superficial and transitional are occasionally used for large intermediate cells.



5 What are superficial cells?


Superficial cells are the most mature cells of vaginal epithelial stages. They are large cells with abundant, angular or folded, blue to blue-green cytoplasm. The cytoplasm may contain a few to many vacuoles, and some cells may contain dark-staining bodies of unknown significance. The nucleus is smaller than that of intermediate cells and may be faded or even absent (anucleate). The maturation process and development of superficial cells are often referred to as cornification, and superficial epithelial cells are sometimes referred to as cornified cells.



6 List the cytologic stages of the estrous cycle.



a. Proestrus

b. Estrus

c. Diestrus

d. Anestrus


7 What are the cytologic features of proestrus in dogs?



a. Admixture of parabasal cells, small and large intermediate cells, and superficial epithelial cells
(1) In early proestrus, parabasal cells and small intermediate cells greatly predominate.

(2) As proestrus advances closer to estrus, the absolute number and percentage of large intermediate cells and superficial cells increase, and these cells become the predominant cell types present on the cytology smears.

(3) About 4 days before the luteinizing hormone (LH) peak, parabasal and small intermediate cells are no longer observed on cytology smears.

b. Usually a few up to many red blood cells (RBCs) and neutrophils are present, although they may be absent. Their numbers decrease in late proestrus.

c. Bacteria, generally small bacterial rods, often are present in high numbers both adhered to the epithelial cells and free throughout the smear. Although generally present in high numbers, bacterial numbers may range from none to many on cytology smears.

d. Mucus may increase sufficiently to give the background of the smear a “dirty” appearance.


8 Are the red blood cells observed on proestrus vaginal cytology smears from vaginal vessels?


RBCs observed during proestrus are not from vaginal vessels; they are erythrocytes exiting uterine capillaries by diapedesis.



9 What is the duration of proestrus in dogs?


In normal dogs, proestrus ranges from 2 to 17 days (depending on the reference source) with a mean duration of 9 days.



10 How do the cytologic features of proestrus in cats differ from those in dogs?


In cats, RBCs and neutrophils are absent, so only the epithelial cells are present. The epithelial cell changes are similar to those in dogs. Also, bacteria may be present.



11 What are the cytologic features of estrus in dogs?



a. Greater than 90% of the epithelial cells are superficial cells (Figure 48-1). These may all be superficial epithelial cells with small pyknotic nuclei, all anucleate cells, or any mixture of the types. Occasionally the cells more closely resemble large intermediate cells (larger nucleus).

b. Neutrophils should be absent. The presence of neutrophils is an abnormal finding and suggests inflammation.

c. RBCs may be present or absent. When present, RBCs come from uterine capillaries.

d. Bacteria are often present in high numbers, although the numbers are variable and bacteria may be absent.

image

Figure 48-1 Estrus. Vaginal smear from a dog consisting of approximately 100% large superficial epithelial cells. (Wright’s stain; 125×.)

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Aug 26, 2016 | Posted by in INTERNAL MEDICINE | Comments Off on VAGINAL CYTOLOGY

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