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March 1972

Partial Ocular Albinism in Mystromys albicaudatus (The African White-Tailed Rat): An Electron Microscopic Study

Author Affiliations

Washington, DC; Bethesda, Md; USA, Washington, DC
From the Armed Forces Institute of Pathology, Washington, DC (Drs. Rodrigues, Fine, Highman, and Streett), and the George Washington University Medical Center, Washington, DC (Dr. Fine), and the National Institutes of Health, Bethesda, Md (Dr. Highman).

Arch Ophthalmol. 1972;87(3):337-346. doi:10.1001/archopht.1972.01000020339020

In a previous study, partial oculocutaneous albinism observed in a colony of Mystromys albicaudatus was found to be due to a paucity of choroidal pigmentation combined with hypopigmentation of the iris, ciliary, and retinal pigment epithelia. By electron microscopy in the present study, the choroidal cells in the adult were observed to possess large numbers of apparently empty vacuoles and no evidence of early melanogenesis. Melanin granules in both immature and abnormal forms were observed in the neuroepithelial layers. Patchy photoreceptor degeneration was also present in the affected adult animals. The pigment epithelium of the affected animals was abnormal from birth, while the neural retina seemed to be normal up to 1 month of age. Further propagation of this aberrant colony of M albicaudatus should permit future determination of the age at which photoreceptors begin to degenerate.

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