Endothelial cell density and characterization of corneal endothelial cells in the Tawny Owl (Strix aluco) using specular microscopy.

OBJECTIVE: To determine endothelial cell density (ECD) and morphology and morphometry of corneal endothelial cells in the tawny owl (Strix aluco), as well as to report the effects of aging on these parameters.

ANIMAL STUDY AND PROCEDURES: Twenty tawny owls were included in the study and classified into 2 groups according to their age: fledglings (<1 year old) and adults (>1 year old). Central corneal endothelium was studied by means of noncontact specular microscopy (Specular Microscope SP-2000P; Topcon, Tokyo, Japan), and results for ECD (cells/mm2 ), mean cell area ((MCA (μm2 )), polymegathism (CV), and pleomorphism (% hexagonal cells) were obtained. Results are described by median, interquartile range (25th, 75th percentiles), and absolute range for ECD, MCA, pleomorphism, and polymegathism. In addition, inferential analyses by Mann-Whitney U test were also performed. A two-tailed Type I error of 5% was established.

RESULTS: Results in fledglings were as follows: ECD = 2864 cells/mm2 , MCA = 348 μm2 , % hexagonal cells = 72.75%, and CV = 21. Results in adults were as follows: ECD = 2602 cells/mm2 , MCA = 384 μm2 , % hexagonal cells = 78.83%, and CV = 16. No significant differences in ECD and MCA were seen between the groups (P > .05), although there were significant differences in % hexagonal cells and CV (P < .05).

CONCLUSIONS: Tawny owls present a uniform endothelium in cell size and shape, although ECD and MCA differ greatly from other bird species. Differences in ECD and MCA could not be found between fledglings and adults probably because of the youth of adult specimens, although there were differences in pleomorphism and polymegathism.