Origin and development of lens cataracts in mumps‐infected chick embryos

Abstract

Abstract Critical inocula of Enders strain of mumps virus were injected over the blastoderm at 36, 48, 60, 72 and 96 hours of incubation (37°C). Surviving embryos were harvested at daily intervals up to 14 days postinoculation. Gross and microscopic observations revealed the lens to be the only organ consistently exhibiting abnormal development following inoculation with mumps virus. By comparison, maldevelopment in other structures was occasionally observed up to the third day postinoculation, but rarely in embryos surviving three or more days. Characteristic lens cataracts were observed, but only in embryos which had been inoculated prior to Hamburger‐Hamilton stage 18, i.e., prior to separation of the lens vesicle from surface ectoderm. An analysis of the histopathogenesis of lens cataracts in embryos inoculated at stages 8–17 indicates that the differentiating lens fibers became progressively more extensively damaged as development proceeded. However, it is evident that the differentiation of new lens fibers proceeded peripherally as the more mature fibers continued to be destroyed centrally. It can be concluded that differentiating lens fibers are highly susceptible to damage by mumps virus, but the initiation of the characteristic defect occurred in our experiments only during the early formative phases of lens development.