Distribution of Lednice (Yaba 1) virus in the chick embryo.

Distribution of Lednice (Yaba 1) virus antigen (LVA) was followed by immunofluorescene (IF) in chick embryos inoculated into the yolk sacs. Positive fluorescence of LVA was observed in neurons and neuroblasts of the developing brain, spinal cord and spinal ganglia as well as in skeletal muscles, heart muscle, vascular endothelium and lung mesenchyma. In the yolk sac, foci of specific fluorescence were occasionally seen in endothelium cells of vessels and in islands of extraembryonic haematopoesis. At sites corresponding to the occurrence of LVA, extensive oedema was accompanied by extravazation of erythrocytes and accumulation of white blood cells. The nature of tissues in which the virus replicates was discussed from the point of view of LVA distribution and the morphological lesions observed.