Lentoid Bodies in the Avian Retina

Summary In-vitro studies suggest that, in avian retina, lentoid bodies arise from Muller cells or developing neuroretina. This report describes lentoid bodies in adult avian retinas in association with retinal trauma or degeneration. Retinal lentoids were identified in four birds (three owls and one parrot) in the course of routine diagnostic histopathology. Sections were stained with periodic acid-Schiff for the purposes of descriptive histology, and immunolabelled for a Muller cell marker (glial fibrillary acidic protein; GFAP) and a lens-specific marker (crystallin alpha-A). Intraretinal lentoids of varying size were identified, the constituent cells resembling bladder cells similar to those seen in cataracts. The process of lentoid formation followed a consistent pattern, characterized by progressive Muller cell hypertrophy in damaged areas, culminating in lentoid formation. GFAP immunoreactivity was strongest in Muller cells in the early stages of hypertrophy and receded as Muller cell hypertrophy advanced and lentoids developed. In contrast to GFAP immunoreactivity, crystalline alpha-A labelling increased in distribution and intensity as Muller hypertrophy became more prominent and lentoids were formed. This represents the first report of intraretinal lentoids in birds in vivo . The immunohistochemical data suggest that they arise from Muller cells. Association of lentoids with retinal damage supports the assertion that they arise following disruption of normal cell–cell communication.