DISCUSSION: effusion cytology and exfoliated cells (7),DISCUSSION: effusion cytology and exfoliated cells (7),

DISCUSSION:             Pap is regarded as the best stain for assessment of oral buccal  smears and ensures maximum resemblance to corresponding cells in histologic sections; however, a prerequisite is usually immediate fixation in 95% ethanol (4). Some degree of air-drying is inevitable particularly at the edges of smears where diagnostic cells often concentrate. Deleterious effects of air-drying on nuclear and cytoplasmic staining are particularly noticeable if the amount of aspirate is small and relatively dry. So, it is highly desirable to use methods to rehydrate these dried up cells. This study revealed that immersion of air-dried pap smears in coconut oil for 10 minutes. In fact, the clearer background was seen in ARF smears rehydrated with coconut oil .The obtained results about nuclear staining showed significant difference between the air dried and wet fixed smear. (table 1)(fig 1). The cytologic staining quality is excellent (×100) when compared to wet fixed smear (table 2)(fig 2). Rehydration of air-dried buccal  smears  showed good background staining properties (table 3) when compared  to wet fix smear. The procedure of air-drying and rehydration is simple, fast, inexpensive and highly. The rehydration time is 10 minutes because this was found to be the optimal time for clearing up the background (5). This renders search for diagnostic cells less tedious and avoids the problem of overlapping of  cells obscuring cellular details. Longer immersion in coconut oil  is detrimental because of nuclear wrinkling. The maximum time of air-drying with well preservation of cellular details was up to four days (6). Rehydration is recommended for several other advantages as well: the smears can be spread more thinly and leisurely, the problem of falling off larger particles or thicker portions of the smear in wet fixation can be avoided, the cells have better adhesion to slides, the cells are flatter and the depth of focus on nuclei is much shallower, which is a great advantage in taking photomicrographs (6). This procedure can  also tried   for FNAC, effusion cytology and exfoliated cells (7), and for other staining methods such as H&E (8), Giemsa (9) and immunohistochemical staining (10- 11). According to the current study, we recommend air-drying for 24 hours and rehydration prior to fixation for blood-stained pap smears in addition to traditional wet fixation or as a substitute for it. Though there was no difficulty in reaching cytologic diagnosis with rehydrated smears, and in fact the results were identical or superior to wet fixed smears, for non-blood stained smears its role is less clear. Nonetheless, the routine use of the method might result in better smears