ABSTRACT
Clearing agents are among the most noxious and hazardous chemicals found in histology laboratories. Xylene has probably been the most commonly used chemical in the histology laboratory despite its hazards. There have been several laboratory tests to replace xylene as clearing agent but most of these commercially available substitutes in some cases are less effective, more expensive,slightly biodegradable and are not readily available. The present study was aimed at evaluating the clearing and dewaxing effect of Eucalyptus(citrodora oil), and Xylene during histological and histochemical tissue processing and staining of some selected organs of adults Wistar rats. Citrodora oil was used alongside xylene to clear livers, kidney, brain, and testicular tissues of adult Wistar rats. The Citrodora oil was extracted from the leaves of eucalyptus plants by hydro distillation method. The physical properties, the phytochemical, Gas Chromatography-Mass Spectroscopy (GC-MS) and Nuclear Magnetic Resonancestudies of the oil were carried out using standard procedures. The tissues were also histologically processed using standard method. The resultsshowed that Citrodora oil was pale yellow in color. The densities of the Citrodora oil and xylene were0.80g/ml and 0.84 g/ml, respectively. The viscosity of the Citrodora oil was 0.34cp and that forxylene was 0.45cp. The flash point of Citrodora was at 350C, while that of xylene, was at 390C. The refractive indexes ofCitrodora oil and xylene were 1.46 and 1.50,respectively. The GC-MS results of Citrodora oil shows that the predominant constituent in Citrodora oil iscitronellal with relative abundance of 42.20% followed by β- Citronellol (21.71%). Xylene contains 94% of o-xylene, 97% of p-xylene, 98% of m-xylene and 98%p-xylene. The nuclear magnetic resonance showed that all the chemical shifts are positive to the reference and are made up of mainly triglycerides. Histological, histochemical and immunohistochemical observation showed that the section quality, the cytoplasmic and nuclear staining qualities appeared to give good contrast in Citrodora oil when compared with xylene. There was no statisticallysignificantdfferences(p≥0.05)in the section quality and staining ability of liver, kidney, brain and testicular tissues of Wistar rats clearedin Citrodora oil and Xylene compared. This present study concludes that Citrodora oil can clear and dewax Wistar rat tissues during tissue and staining processes for histological, histochemical and immunohistochemical tissue processing and staining as xylene.