Applied Anatomical and Morphological Characterization of the Ocular Surface of the African Spiny Mice: Acomys cahirinus

Purpose: The Acomys cahirinus (A. cahirinus) are a valuable animal model for studying adaptations to dry harsh climates. Recently, Acomys have emerged as a powerful model for studying tissue regeneration: regenerating large sections of skin tissue without scarring. This study characterizes the anatomy and morphology of the ocular surface and accessory glands of the A. cahirinus. Methods: The ocular surface was assessed, and cornea and accessory glands collected for A.cahirinus at 3 months, and CD-1 mice at 8 weeks. The corneas were imaged by optical coherence tomography (OCT), in vivo confocal microscopy (HRTIII), and under a stereomicroscope with white light and a ring light. Tissues were collected and processed for histological analysis, and stained with hematoxylin and eosin (H&E), periodic acid-Shiff staining (PAS), and alcian blue, and processed for immunostaining. Results: A. cahirinus present pockets of cells within the corneal epithelium with features of epithelial progenitor cells, and fibrovascular ridges within the limbal region that contain limbal epithelial stem cells. A. cahirinus present few Meibomian glands (MGs) within the lower lid, however, they present large MGs that extend laterally and posteriorly from the temporal eyelid margin. Clusters of serous glands are present at the most distal region of these MGs. Lacrimal glands were identified with serous secretion, and harderian glands were identified with apocrine secretion. Conclusions: The A. cahirinus present key adaptations that enable them to maintain a healthy ocular surface despite living in a semi-arid climate and are a powerful model for identifying mechanisms to prevent dry eye disease and to promote scarless regeneration in mammals.