X-rays and the Retina of the Primate Fetus

Thirty pregnant monkeys (Macaca mulatta) were x-rayed (200 to 400 R) with radiations coned to the fetus between gestational ages of 60 to 145 days to study the retinal radiosensitivity, damage, and possible repair over a 23-ndonth period. 1rradiation even at 60 days resulted in extensive necrosis of retinal neuroblasts followed by reorganization with rosette formation. The most posterior region of the developing retina is the first to differentiate from neurectoderm to neurons, through the highly radiosensitive neuroblast stage. Differentiation proceeds anteriorly toward the ora serrata, with a parallel wave of radiosensitivity. No fetal retina can be completely damaged by a single x- irradiation. Attempts to reorganize show deficits resulting in bizarre formations of the retina that persist after birth. Clinicians are cautioned that the mammalian retina exhibits radiosensitive areas during the major part of gestation. (auth)