Neuroepithelial bodies in the lung of the tree frog, Hyla arborea L. A scanning and transmission electron microscopic study.

The endocrine-like cells (ELC), which together with nerve endings form the neuroepithelial bodies, are located on primary and secondary septa in the non-ciliated epithelium of the lung of Hyla arborea. ELC protrude markedly toward the lumen of the lung and are surrounded by pneumocytes, which separate ELC from the lumen by thin cytoplasmic processes. ELC possess a light cytoplasm containing two types of granules: (i) numerous small granules, 50-110 nm in diameter, and (ii) single large granules, 290-860 nm in diameter. Numerous nerve fibers, often forming synaptic junctions, can be observed in contact with ELC.