Immunofluorescence of Newcastle Disease Virus in Paraffin Embedded Tissues of Early Chick Embryos. ∗

Abstract

Summary

Paraffin embedded tissues have been found to be suitable for immunofluorescent studies of Newcastle disease virus-induced defects in chick embryos inoculated at early stages of incubation. In embryos inoculated at 48 hours incubation and harvested 16 to 24 hours later viral antigen was observed in many tissues of the embryo proper and in cells of the extraembryonic membranes. The viral antigen was most concentrated in the organs subject to the virus-induced developmental defects, i.e., in tissues differentiating from the body ectoderm, including lens primordia, auditory vesicles, visceral arch ectoderm, olfactory epithelium and it was also found in the visceral arch mesoderm and in the epimyocardium of the heart. However, virus was not restricted to these tissues but was also observed in some cells of the general body ectoderm and was widely distributed in cells of the chorion, amnion, and in the yolk sac entoderm. In late infections the specific viral fluorescence was also seen in mesodermal tissues directly underlying the affected ectoderm. Thus viral antigen was found to be distributed in cells derived from all three of the primary germ layers, ectoderm, entoderm, and mesoderm.