Baseline histological and morphometric description of the retina in the Pied Crow (Corvus albus)

The Pied Crow (Corvus albus) is a visually guided diurnal corvid widely distributed across sub-Saharan Africa, yet detailed descriptions of its ocular microanatomy remain limited. This study provides a concise histological and immunohistochemical characterization of the retina from an adult male specimen obtained through an ethically approved wildlife surveillance programme. Hematoxylin and eosin staining, Alcian Blue staining, and NeuN immunolabeling were used to document retinal organization and neuronal localization. The objective was to generate baseline morphological data for this species.

The retina exhibited a well-organized multilayered structure typical of diurnal avian species, supported by a prominent hyaline scleral cartilage plate. The outer nuclear layer contained 3-4 rows of nuclei, consistent with the duplex organization of avian retinas. Total retinal thickness measured approximately 303 μm, with the ganglion cell layer measuring ~ 27 μm. NeuN immunolabeling showed strong nuclear immunoreactivity in the ganglion cell layer and moderate labeling in the inner nuclear layer. NeuN-positive neuronal somata in the ganglion cell layer ranged from 2.4 to 5.8 μm in diameter. These findings provide baseline histological and morphometric reference data for Corvus albus, contributing foundational information for future comparative and functional investigations.