Purpose
Antibodies against the calcium binding protein calretinin are known markers for AII amacrine cells in the retina of some but not all mammalian species. The aim of this study was to identify the calretinin positive cells in human retina.
Methods
Post mortem donor eyes were obtained with consent from the Lions’ NSW Eye Bank. Vertical Vibratome sections were cut along the horizontal meridian and processed for calretinin immunofluorescence. Other retinal pieces were pre-labelled with antibodies against calretinin and subsequently immunopositive cells were injected with the lipophilic dye DiI.
Results
The large majority of calretinin immunoreactive cells were found in the inner nuclear layer (INL) but some were present in the ganglion cell layer (GCL). Most cells in the INL had AII morphology; in addition a wide-field amacrine cell type with the morphology of the semilunar amacrine cell (Kolb et al., 1992) was identified. In the ganglion cell layer about 80% of calretinin immunoreactive cells were displaced amacrine and about 20% were ganglion cells. The displaced amacrine cells were classified as stellate, semilunar and thorny cells. The ganglion cell type(s) remain to be identified.
Conclusions
Antibodies against calretinin can be used to identify AII amacrine cells in the inner nuclear layer and wide-field amacrine cells in the ganglion cell layer.