[Population of hair cells in the Corti's organ of shrews].

In shrews (family Soricidase) the organ of Corti was examined by means of the surface specimen technique. The analysis of the qualitative deviations from the normal cellular pattern of Corti organ was based on more than 160 ears of shrews (Sorex araneus, S. minutus, Neomys fodiens, and Crocidura suaveolens). The dislocation, rotation, malformation of hair cells, and one finding of the giant outer hair cell are described. The quantitative analyses of the population of hair cells are based on 61 ears of Sorex araneus divided into 2 age groups. The mean values of aplasias and of missing and supernumerary hair cells in dependence on individual rows and half-turns of cochlea are given. The loss of hair cells depends on the age of the animal. The findings of aplasias and supernumerary outer hair cells (especially those of atypical 4th row) are relatively frequent in shrews. The organ of Corti in shows has a very regular arrangement; deviations of all types are scant and thus we may hold the ideal cochleogram for the norm. The found deviations seem to have no functional meaning.