Drying paraffin sections on hotplate unadvisable

Abstract

Previous study indicated that heating of paraffin sections at 90-140�C prevented their detachment from slides, but their thickness was reduced by half and staining affected with structures even disappearing. This study aimed to determine the effects of section drying at a temperature lower than the melting point of paraffin. 6 serial sections (thickness set at 10 ?m) were cut from each of 12 paraffin embedded testicular tissue blocks, with 3 sections (control, randomly sampled from each block) placed vertically at room temperature immediately after floating onto slides from water bath (37�C) and the other 3 heated on hotplate at 54�C for 2 hours for a complete drying. No sections detached during staining with hematoxylin. In comparison with control sections, the mean area of heated sections was unchanged but histological damage occurred. The damage varied from slight enlargement of the inter-tubular space or the tubular lumen (seen on most of the sections) to overturning or missing of the seminiferous tubules (seen on approximately 1/3 of the sections). Besides, the mean thickness of heated sections was reduced to 85% of control. We therefore concluded, among others, that it is not advisable to dry paraffin sections on hotplate.