Ultrastructure of the supporting cells in the paratympanic organ of chicken,Gallus gallus domesticus

Abstract

The paratympanic organ is a specialized sensory organ of birds located in the medial wall of the tympanic cavity. It possesses a sensory epithelium formed by type II hair cells and supporting cells. The supporting cells are tall, narrow units that extend from the basement membrane to the free epithelial surface. They show a fine structure characterized by numerous mitochondria, a conspicuous Golgi complex and a well‐developed RER. Moreover, some uncommon structures, probably formed by heaped RER cisternae, are frequently present in the cytoplasm. Adjacent supporting cells are connected by numerous and extensive gap junctions; moreover, small gap junctions between hair cell and supporting cells are to be found. The possible mechanical and metabolical functions of the paratympanic organ supporting cells are discussed. J. Morphol. 236:65–73, 1998. © 1998 Wiley‐Liss, Inc.

The paratympanic organ: a barometer and altimeter in the middle ear of birds?

“…The stereocilia and the kinocilium have a typical morphological orientation relative to the long axis of the PTO (Jørgensen, '84), suggesting the measurement of fluid and cupula movement along this axis. Support cells may contribute to the fluid composition of the vesicle (Ruffoli et al, '98). The sensory hair cells receive both afferent and efferent innervation from myelinated and unmyelinated nerve fibers.…”