Figure 1. YFP expression following transduction of primary cultures of chick embryonic cells with FIV-YFP vectors.

Primary cell cultures from E11 chick embryos were transduced with FIV-YFP (2×10⁴ TU/well, in a 24-well plate) and YFP-expressing cells (green) were detected by fluorescence microscopy, 48 h after transduction (A–F). The corresponding bright-field micrographs of the same cultures (A′–F′) demonstrate the tissue-specific morphology of the cells. Scale bar = 20 µm. Rate of transduction in each culture, determined by FACS analysis, is shown in Figure S2.