The present study shows that aniline blue can be used as a fluorescent stain for glycogen. The dye is also helpful in tracing pathological and autolytic changes in lysosomes, mitochondria, erythrocytes and nuclei, and it can also be used for demonstrating bacteria in tissue sections and smears. The techniques used are simple, rapid and inexpensive. Spectrophotometric studies on aniline blue solutions have shown that aniline blue fluorescence was enhanced by the addition of certain proteins, or of glycogen to the dye solution. In case of albumen which has the maximum effect, enhancement is dependent upon the albumen-dye ratio. The mechanism of staining is mainly due to self quenching, but there is also an evidence of the presence of hydrophobic reaction.

K E Y WORDS. SEM, fracture technique, paraffin embedding, soft animal tissues, internal structure. S U M M A R YA simple, rapid, economic and reliable method was used for visualization of internal structure of soft tissues by fracturing paraffin embedded samples at room temperature. The same sample which was used for light microscopy was then fractured for SEM. Most of the cellular and extracellular details are exposed without any need of special equipment. The technique preserves the architecture of tissues and can be used in routine diagnostic pathology. I N R O D U C T I O NThe SEM has greatly expanded the knowledge of the anatomy of various organs and tissues but a limiting factor in its use is the difficulty of visualization of internal structure at both histological and cytological levels. Also tissue preparation for SEM is still difficult and expensive (Buss & Hollweg, 1980). In this work a simple and economic technique was used by fracturing (at room temperature) paraffin embedded tissues originally prepared for light microscopy examination. MATERIALS A N D M E T H O D SNormal male Sprague Dawley rats (250-350 g) were used. All animals were killed by decapitation. Tissue samples were taken within 5 min of death, and the blocks were subsequently trimmed to size 5 x 5 x 2 mm. All tissues were fixed by immersion in either phosphate buffered formalin (pH 7-2) or 31,'0 phosphate buffered glutaraldehyde (pH 7.2) for at least 24 h. Tissues were then embedded in paraffin using the routine procedures. Preparation for SEMAfter taking sections for light microscopy, the wax blocks were treated as follows: 1. Wax blocks were removed from the plastic casettes. The wax was cut with a hot razor blade on either side of the block without cutting into the tissue. The direction of the cuts was either from side to side or from corner to corner. To avoid cracking of the wax prematurely during cutting, minimal pressure with the heated blade was applied. The blade was reheated when excessive resistance was felt during cutting.2. The block was held between fingers and manually fractured along the plane of cuts. 3. Thin pieces of tissue (0.5 mm thickness) bearing the fractured surfaces were cut from each fractured piece of tissue using a warm razor blade. The remaining tissue in the blocks was labelled for future use if needed.

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