The Number and Distribution of Mast Cells in Monkey Lungs1–3

We estimated the number of mast cells in monkey lungs by both quantitative histologic examination and measurement of total lung histamine, and showed that monkey lungs contain between 107 and 108 mast cells, with approximately 83 per cent of these being located in conducting airways, and 17 per cent in the parenchyma. The number of mast cells found in each airway generation increased from approximately 60,000 in the trachea to 8 million in the terminal bronchioles. In airways from different generations the number of mast cells superficial to the basement membrane in the epithelium and lumen (EMC) was compared to the number of mast cells found in the submucosa between basement membrane and cartilage and to the number of those found outside the cartilage. The number of EMC varied between animals and ranged from 0–0.4 per cent of the total number of mast cells in the trachea, to 0–27 per cent of the total in the terminal bronchioles. On the average, EMC accounted for 12 per cent of the total number of mast c...