The Feulgen-Picric-Acid block Stain Additional Data

Abstract

Additional experiments on staining of tissues in the block by means of picric acid and the Feulgen reaction (Lhotka and Davenport, 1947) show that a variety of tissues from both plant and animal sources will respond favorably. An attempt to combine fixation and staining into a single step was not successful for mammalian tissues, but gave fair results on frog. Fixation in sublimate-acetic was unsatisfactory for block staining, and conversely, fixation in sulfosalicylic-picric gave poor Feulgen stains on the slide. Soxhlet extraction of tissue with absolute alcohol removed Feulgen positive, non-nuclear material with the exception of that in vascular endothe-lium, cartilaginous matrix and elastic tissue. After such extraction, similar results were obtained with both block and slide methods of staining.