Quantitative study of bronchial mucous gland enlargement.

Histological sections from 30 lower lobe bronchi, taken from coalminers' lungs collected for the British National Coal Board's Pneumoconiosis Field Research, were selected according to the proportion of mucous gland area occupying the non-cartilaginous part of the bronchial wall. The total gland area expressed as a percentage of the non-cartilaginous wall was called the gland index. Estimations were made of the total number of gland cells and acini on a section and of their numbers per unit area of gland. These estimations were compared with the gland index. The total numbers of gland cells and acini were found to be directly related to the gland index (r=0.84 and 0.86), whereas no relationship was found between the number of gland cells or acini per unit area of gland and the gland index (r=0.08 and 0.02). This indicates that bronchial mucous gland enlargement is primarily a hyperplastic change. A direct relationship between the numbers of gland cells per unit area of gland and acini per unit area gland was found (r=0.69), and this suggests that acinar enlargement is likely to be caused by accumulation of mucus in the acinar lumen.