Immunolocalization of calbindin D28k and calretinin in the dog cochlea during postnatal development

The calbindin (CB) and the calretinin (CR) immunoreactivities were studied in the dog cochlea during its postnatal maturation from birth to the 33rd p ostnatal day. At birth, CB was expressed in the Kolliker's organ, in the im mature inner (IHC) and outer hair cells (OHC), in neurons of the spiral gan glion, and in nerve fibers running in the basilar membrane of the apical tu rn. During the cochlear maturation, non-sensorineuronal structures, such as the Kolliker's organ, the rods of Corti, and the inner sulcus cells, displ ayed a transient CB-staining. In the adult-like dog cochlea, CB was found i n the cytoplasm, the cuticular plate, and the stereocilia of the IHC and OH C. All the neurons of the spiral ganglion and some nerves fibers in the mod ulius were CB-positive. At birth, CR exhibited a neuronal distribution: abo ut 75% of the spiral ganglion neurons, some nerve fibers in the modulius an d nerve fibers running in the basilar membrane were CR-labeled. During the postnatal maturation, a CR-immunostaining appeared around the IHC body and CR was expressed transiently in the OHC. In the adult-like dog cochlea, a C R-positive network surrounded the unlabeled IHC. The neuronal CR-labeling r emained unchanged from birth. (C) 2000 Elsevier Science B.V. All rights res erved.