Ultrastructural changes in the size of mast cell granules and in the granular matrix during an experimental...

A staining method for the identification and the functional characteristics of mast cells in semithin section is described. Transmission electron microscopy in the conditions of an experimental anaphylactic shock (EASh) was used to measure microplanimetrically the longest diameters of the non-secreting (NG) and the secreting (SG) granules. Determined was also the percent ratio between these 2 types of granules of the mast cells. Under normal conditions (control animals) 96.2% of the granules were NG, and nearly half of them (48.7%) had a diameter (mast cell granule diameter--McGD) shorter than 1.0 micron (1,000 nm). In the conditions of a lethal EASh 87.7% of the granules were SG, and most of them (54.4%) had McGD longer than 1.5 micron (1,500 nm). In EASh a considerable part of NG (6.2%) also had McGD longer than 1.5 micron (1,500 nm). In mast cell degranulation the electron dense or fine lamellar structure of the granular matrix was often disturbed. Tiny, oval, and randomly dispersed particles appeared. It was admitted that if the areas among the particles of a size lower than 0.2 micron (200 nm) were prevailing the granular matrix disorganization (GMD) was of type (SG1); if most of the areas were larger than 0.2 micron (200 nm) GMD was of type II (SG2) and preceded the complete fusion of the granules.