OBJECTIVE: To demonstrate the organization of the spiral ganglion in the mammalian species.

METHODS: Temporal bone (TB) specimens from man (n = 2), monkey (n = 2), lion (n = 2) and cat (n = 20) were stained, decalcified and dissected according to the Sudan black B method of Rasmussen. These TB specimens were examined under a Zeiss operating microscope and photographed with a Canon 100 camera interfaced with the microscope.

RESULTS: Spiral ganglion cells occurred in clusters within Rosenthal's canal in all four species. The location of the clusters was marked by the interface between axon and dendritic bundles as well as groups of ganglion cells. In monkey and man the clusters were more separated than in lion and cat.

CONCLUSIONS: These observations indicate that the spiral ganglion forms clusters of neurons within Rosenthal's canal at the basal cochlear turn in the mammals investigated here. The formation of clusters may be related to the principles of neurogenesis.