Brush-like cells within bronchial epithelia of chicken lung (Gallus gallus).

The secondary and primary (mesobronchus) bronchi of chicken lung are lined by a typical respiratory epithelium: pseudostratified columnar ciliated with goblet cells. Up to date, four constituting epithelial cell types have been identified: ciliated, mucosecretory, basal and endocrine cells. In this study a putative new epithelial cell type, the brush-like cell, is described. The avian brush-like cells have only been found in the bronchial epithelia but never in the gas-exchange areas. They are scattered among the other epithelial cells, mainly ciliated cells, and their number is extremely low. The characteristic morphological feature of these cells is an apical protruding cytoplasm with microvilli. This cell type is similar to that found in the lung of some mammalian and non-mammalian species. The functional role of these cells is not yet clear; they could carry out absorptive processes.