Fig. 12
From: Functional morphological study of the choana in different bird species
Photomicrograph of a transverse section of hoopoe shows the epithelium roof is non-keratinized (double arrows), appears only to cover the papillae (head arrow), then changes gradually into pseudostratified ciliated columnar epithelium (arrow) with simple alveolar gland (star). Upper right shows goblet cells (Gc) within pseudostratified ciliated columnar epithelium (head arrow) and simple alveolar gland (star). (H& E)