RAPID PERMANGANATE-FIXATION AND ALCOHOL-DEHYDRATION OF FUNGAL SPECIMENS FOR TRANSMISSION ELECTRON-MICROSCOPY

The proposed method was developed primarily for ultrastructural documentation of the fungal cell envelope. The features include embedding live cells in small cylinders of 1% agar, using a relatively high concentration (5%) of unbuffered potassium permanganate, shortening the contact time to 2 min and transferring the specimens into 50% alcohol as quickly as possible. The casting of agar cylinders is facilitated by using uniform-bore capillary tubes. The treatment of embedded specimens with permanganate and the subsequent washing and dehydration steps are all carried out in one small screw-capped bottle which is mounted on a rotator; solutions are introduced by pipette and removed by suction. The method has been used extensively with strains of Sporothrix schenckii to distinguish conidia from yeast-like cells under diverse cultural conditions. Candida albicans and eight other species of fungi yielded informative electron micrographs with this method.