A spontaneous corneal change in juvenile Wistar rats.

Corneal changes were seen in a shipment of male and female Charles River Wistar (Crl:(WI)BR) albino rats aged 33 days. Seventeen weeks later, varying degrees of corneal roughness were observed ophthalmoscopically in 40 of 43 males and 26 of 29 females. Corneal lesions, described clinically as multiple punctate or particulate opacities, were most often bilateral and located paracentrally. Histologically, lesions were observed in only 21 of 40 males and in 15 of 26 females which had shown clinical changes. The lesions consisted of basophilic particulate material, which occasionally formed linear plaques, lining the basement membrane of the corneal epithelium. Ultrastructurally, irregularly distributed electron-dense deposits, occasionally assuming a concentric laminar appearance, were observed. X-ray microanalysis revealed that the granules consisted predominantly of calcium and phosphorus, with trace amounts of iron, zinc, sodium and aluminium. These mineral deposits in the corneas of Wistar rats were similar to those described in other species. Awareness of this spontaneously occurring disease in Wistar rats is of importance in relation to toxicological investigations in which the cornea may be a target organ.