Elemental composition of mast cell granules of the rat and tree frog: X-ray Microanalysis on fresh frozen dried ultrathin sections

Abstract

Electron probe x-ray microanalysis using fresh air-dried spreads revealed electrolyte elements in the granules of platelets, mast cells, pancreatic acinar cells and melanocytes. Mast cell granules of the rat and tree frog are quantitatively compared by an energy dispersive spectrometry (EDS) using fresh frozen dried ultrathin sections.Adult Wistar rats (ca. 250 g) and tree frogs (Hyla arborea japonica) of both sexes were used. Fresh frozen dried smears of rat peritoneal mast cells were prepared on the collodion-membrane covered titanium grid. Fresh frozen dried ultrathin sections of the tongue of the rat and tree frog were made by the metal contact method employing the rapid freezing apparatus (RF-2) cooled with liquid nitrogen. Ultrathin cryosections (60 nmj were cut at 163 K, transferred to the frozen specimen treating apparatus (FD-2) for freeze-drying in high vacuum at 173 K for 74-96 h. The specimens were observed first by 200kV transmission electron microscopy (TEM) and then under the scanning analytical electron microscope (X-650) for scanning transmission electron microscopy (STEM) images at an acceleration voltage of 40 kV and a specimen current of 0.2 nA.