Distribution of S100 immunoreactivity in the retina and optic nerve head of the teleost Tinca tinca L.

The distribution of S100 immunoreactivity within the normal and regenerating retina and optic nerve head of the teleost Tinca tinca L. has been investigated using the avidin-biotin complex (ABC) method and a polyclonal antibody against S100. Astrocytes and Müller cells were labeled with this antibody. This represents the first description of astrocytes localized in the optic nerve head and in the nerve fiber layer of the fish retina displaying a typical bipolar morphology. Horizontal cells in the inner nuclear layer were immunolabeled; we also observed species-specific S100 labeling of horizontal cells of the H1 subtype. No significant changes were seen in the S100 immunoreactive Müller cells, astrocytes, or horizontal cells in the tench retina after optic nerve crushing and during regeneration. These results might help to understand the function of glial cells in the normal and experimentally induced regenerating fish visual system.