Abstract
Discrete groups of 20-25 nm isometric particles, considered to represent maize rayado fino virus (RFV), were consistently observed in the ectoderm, fat body, midgut, follicular cells of the ovary, muscle and salivary glands of RFV-infected D. maidis. The particles commonly occurred within cytoplasmic bodies bound by membranes, some of them resembling lysosomes, and were not found in nonviruliferous insects. These findings are congruent with previous studies on the multiplication of RFV in D. maidis. The absence of cytopathologic effects due to viral infection at the ultrastructural level confirms biological data on the absence of deleterious effects of the virus in its vector.