Histochemical and immunohistochemical study of the effect of exposure to sulphuric acid fumes on the larynx of the rabbits
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Sulphuric acid (SA) is used in innumerable industrial processes. In this work the effect of exposure to SA fumes for various periods at different duration on the larynx of the rabbits was evaluated histochemically and immunohistochemically. This study was conducted on 50 healthy rabbits divided into control group comprised 5 animals not exposed to SA and experimental group comprised 45 animals divided into three equal groups (15 in each) expqsed to SA fumes daily hCfr,t,V for 30, 60 and 120 minutes respectively. Each prouppubdivided into three equal subgroups (5 in each) according to the period of exposure; one, two or three weeks. The fumes were pumped through a hole in the side of glass box using an electric nebulizer at concentration 1 mg/m3 .The larynxes of all animals were stained histochemically by Masson trichrome, Orcein, PAS, Alcian blue and silver stained nucleolar organizer regions (AgNORs) and immunohistochemically by Ki-67. The results showed that after exposure to SA especially at longer periods and long durations there was increase of the thickness and disturbance of stratified and respiratory epithelia, ',Increase of collagen fibers and decrease of elastic fibers. There was increase of the numbers of glands and increase of neutral and acidic mucosubstance. There was increase of both m AgNORs and P AgNORs >1 of both epithelia .Also, there was increase of Ki-67 PI and the reaction was not restricted to the basal layer. This means that SA exposure caused increase of the ploidy and proliflerative activities of the epithelia of the larynx especially after long period and duration. From this work it can be concluded that the exposure to sulphuric acid fumes especially at longer periods and long durations have a carcinogenic effect on the larynx. So, it is recommended that workers exposed to SA their larynx must be examined periodically.