THE MAST CELLS 



as far as the fluorescent bodies are concerned, but the toluidine blue reveals 

 many mast cells which had not previously shown fluorescence. In general, 

 the mast cells which took up the diamidine in the short-term experiment are 

 the large, pericapillary metachromatic mast cells, recognized as adult or ripe 

 mast cells ('type-II cells'). These fluorescent type-II cells are well seen in the 

 peritoneal interspaces of the mesentery and in the fatty fringes attached to the 



Fatty uterine fringe from rat killed by the slow intravenous injection of 2 -hydroxy stilbamidine, 

 stained with toluidine blue. The young type-I mast cells in the adventitia of the main vessel 

 appear normal, but vacuoles are already forming in the more mature type-II cells near the 

 capillaries. Had the animal survived longer these type-I I cells would have undergone complete 

 disruption (X455). (Riley (1953), J. Path. Bad. 65, 471.) 



uterine horns. So far as can be ascertained the fluorescence is confined to the 

 granular cytoplasm of the mast cells, the nucleus being sometimes represented 

 by a central non-fluorescent space. In the omentum the fluorescent mast cells 

 appear principally in the milk spots ('taches laiteuses'), and here practically 

 every mast cell in one milk spot may show fluorescence, whereas an adjacent 

 milk spot may be devoid of fluorescence. It is noteworthy that under the 

 conditions of the present experiments fluorescence is not observed in the 

 numerous mast cells in the subcutaneous connective tissue, although as judged 

 by ordinary staining methods all types of mast cells are present there. 



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