Basilar papilla of the canary and zebra finch: A quantitative scanning electron microscopical description

Morphological parameters of the apical surface of canary and zebra finch basilar papillae were quantitatively evaluated by scanning electron microscopy. The papillar length is 1.6 mm in both species. The zebra-finch papilla has a larger number of hair cells and is wider in the apical half of the papilla as compared to the canary. These two small songbird species have the smallest number of hair cells and the smallest papillae of the bird species investigated to date. The orientation of the hair cells is much more homogenous as compared to other species. Also, the discrepancy in the number of stereovilli of neural and abneural hair cells is much larger than in other bird species. A detailed analysis of gradients across the papilla in the canary revealed that anatomical parameters change in the neural half, whereas they remain rather constant in the abneural half of the papilla. There were, however, no obvious borders that separated distinct hair cell populations in either species