AbstractThe aim of this study was to determine the optimal conditions for the processing and staining of specimens obtained by fine needle tissue aspiration biopsy (FNTAB) of the testis. We assessed the 5 most commonly cited fixative solutions, the 6 most popular staining schedules, the effects of 6 hour and overnight dehydration and infiltration cycles, and 2 slide incubation temperatures. Comparisons were obtained from sources allocated by 5 independent observers to 7 histological features from 20 specimens.Sections incubated at 37°C prior to staining were graded significantly higher than those incubated at 60°C. Similarly, samples processed on the overnight dehydration and infiltration cycle were found to be better preserved than those processed on the 6 hour cycle. Phosphate buffered formalin and zinc formalin were graded significantly lower than the other fixatives for all features. Scores allocated to zinc sulfate, Bouin, and Stieve solutions differed slightly. Stieve solution was selected for FNTAB because of its proven ability to maintain the immunoreactivity of testicular tissue.The various staining techniques highlighted different elements of the tissue, with the Giemsa and hematoxylin&eosin schedules providing the best overall representations. A slight variation ofthe hematoxylin&eosin schedule was selected for FNTAB as it provided particularly clear nuclear definition. (The J Histotechnol17:111, 1994)