Introduction. Currently, tobacco smoking is common among young people, which is a major cause of morbidity and premature mortality, mainly by heart diseases, stroke and brain tumors [6, 13, 14].For biological indication and quantitative assessment of the toxic effects of tobacco smoke on the human body it is preferably to use the method of analysis of chromosomal aberrations of human oral epithelial cells; at the same time, their morphological features remain poorly studied [1, 3, 4]. Buccal smears have several advantages for cytodiagnosis of groups of people: firstly, they safely provide a sufficient number of cells and make it possible to perform re-analyses, and secondly, ensure evaluation of both the general and local action of pathogens [7, 8]. That is, the buccal epithelium is highly informative in the diagnosis of many diseases (bronchial asthma, ulcerative colitis, Crohn's disease, etc.), as well as metabolic disorders in general [12]. Accordingly, the objective of this paper is to study the microscopic features of buccal epithelium in smoking students of Indo-Dravidian race.

Materials and methods. The experiment involved 20 2nd year students of the Faculty of general medicine and pediatrics of Medical Institute, NRU «BSU» in Belgorod (Russian Federation), coming from the Republic of India, the middle-aged (18-21 years) [10], male, without concomitant somatic or mental disorders. All students were divided into 2 groups each of 10 people. The first group included students smoking 6-8 cigarettes per day with 2-3 years of smoking experience, and the second consisted of non-smokers. The material sampling was carried out at one and the same time of day. Using a spatula, the swab of buccal epithelium was taken from the mucous surface of a cheek. The native preparation was prepared, and then stained with hematoxylin-eosin. The objects were studied on a microscope OLYMPUS CX21, with further photographing and imaging (Motic Images Plus 2.0). After that, a licensed program «LpSquare v5.0 for Windows» was used to measure the areas of both nucleus and cytoplasm of buccal epithelial cells with further determination of the nuclear-cytoplasmic ratio (NCR). Data with a significance level of p≤0.05 were considered reliable as compared to control.

The research results revealed that the epithelial cells of non-smoking students are mainly located separately from each other. The spinous cells are of polygonal shape with rounded nuclei and a pale pink cytoplasm contains a moderate amount of granular inclusions. Horny scales are visible extremely rare.

The smear of the experimental group as compared with the control had tightly arranged groups of epithelial cells found, with multiple white blood cells therebetween. Also, the epithelial cells of smoking students have scored nuclei appearing, as well as with «tongue»- and «broken egg»-type protrusions, and some of them contain micronuclei. The cell dimorphism and dual-core cells are rarely revealed (Fig. 1 a-d).

Fig. 1. Buccal epithelial cells of smoking students.Arrows indicate: a) binuclear cells; b) tongue-type protrusion;

c) broken egg-type protrusion; and d) micronucleus. Haematoxylin and eosin stain. Magn. *400.

We also found that the area of the cytoplasm of buccal epithelial cells of the control students as compared with the experimental ones was 35.00% more (p≤0.05), and the nucleus area was 1756% less (p≤0.05), respectively. At the same time, the smokers had nucleocytoplasmic ratio significantly increasing by 47.98% (p≤0.05) as compared to control (Table 1).