Histology of fetal eyes with oculocutaneous albinism
K. Akeo, S. Shirai, S. Okisaka, H. Shimizu, H. Miyata, A. Kikuchi, T. Nishikawa, K. Suzumori, T. Fujiwara and A. Majima
Department of Ophthalmology, National Defense Medical College, Saitama, Japan.
The diagnosis of tyrosinase-negative oculocutaneous albinism (OCA) was made
in a 19-week-old fetus by skin biopsy. Because the parents had an
11-year-old son with tyrosinase-negative OCA, they requested that the fetus
be aborted at the 20th week of gestation. A histological analysis of the
eyes was performed. Throughout the retina, the ganglion cell layer was
separated from the inner neuroblastic layer by the inner plexiform layer.
However, the number of ganglion cells was decreased and the nerve fiber
layer was immature. Bipolar and horizontal cells had begun to segregate
into the inner nuclear layer. Rods and cones were identifiable in the
posterior, but not peripheral, retina. Cones were more numerous in the
center of the retina, and no rod-free area was identifiable. In addition,
the ciliary body (epithelial folds, blood vessels in the mesodermal
connective tissue core, and ciliary muscle) was less developed than in a
normal fetus. Melanosomes in the retinal pigment epithelium only contained
filaments without melanization and were therefore classified as stage I or
II melanosomes. However, the ciliary epithelium also contained some stage
III melanosomes with melanin adherent to the filaments.
