Immunolocalization of the calcium binding S100A1, S100A5 and S100A6 proteins in the dog cochlea during postnatal development

The immunolocalization of three members of the S100 calcium-binding protein family was investigated in the dog cochlea during normal postnatal develop ment. Sections of decalcified and paraffin-embedded cochleae from 16 beagle puppies aged from birth to 3 months were treated with polyclonal antisera raised against the human recombinant S1001, S100A5, and S100A6 proteins. At birth, in the dog cochlea, S100A1 was expressed in the immature Deiter's c ells, and slightly in the pillar cells. From the second week, S100A1 was de tected in the supporting structures of the organ of Corti, i.e. the Deiter' s, the pillar, the border, and the Hensen's cells, and in the reticular mem brane. From birth onwards, S100A5 remained a neuronal-specific protein, onl y located in a subpopulation of neurons in the spiral ganglion. S100A6 was not expressed at birth. From the second week of life, the Schwann cells and nerve sheaths in the modiolus, in the spiral ganglion, and running in the direction of the organ of Corti exhibited S100A6-labeling. From the 12th po stnatal day, some scattered intermediate cells started to express S100A6 pr otein in the stria vascularis. The number of labeled intermediate cells inc reased during the third week. At adult stage, the intermediate cells were S 100A6-stained with cytoplasmic labeling throughout the stria vascularis fro m the base to the apex of the cochlea. None of the other cochlear structure s expressed the S100 proteins under study during the postnatal development of the dog cochlea. The S100A1, S100A5, S100A6 immunostaining was limited t o specific cell types in dog cochlea. These S100 proteins were useful marke rs in the study of supporting cells, neurons, nerve fibers sheaths and stri a vascularis (S100A6) during the normal postnatal development of the dog co chlea. (C) 2001 Elsevier Science B.V. All rights reserved.