Solitary granular endocrine cells and neuroepithelial bodies in the lungs of the ringed turtle dove (Streptopelia risoria).

The presence of granular endocrine cells was investigated in the lungs of 4-6 weeks old Ringed Turtle Doves (Streptopelia risoria) by scanning and transmission electron microscopy. No granular cells were observed with the scanning electron microscope. In alternate semithin and ultrathin sections granular cells were found either singly or in small groups in the ciliated parts of the epithelium, and in relatively large clusters of between at least five and sixteen cells in the unciliated flat regions including the primary bronchus around the orifices of the lateroventral bronchi, and the roots of the medioventral, mediodorsal and lateroventral bronchi. Within the clusters the granular cells were frequently separated by attenuated profiles of highly electron-dense cells with microvilli. Naked axonal profiles which contained numerous agranular vesicles and occasional large granular vesicles were observed above the basal lamina lying close to the granular cells. Synaptic structures associated with the cells were found. This description of clusters of innervated granular endocrine cells in the dove appears to be the first account of neuroepithelial bodies in the lungs of birds.