FIG. 1.

GFP-transgenic pigs are a source of GFP+ progenitor cells. Viewed under fluorescent illumination, a near-term piglet exhibits widespread green fluorescence, particularly in the hooves and snout (A). The eye of a 43-day gestational age GFP-transgenic fetus (NT92 line, this example only) shows an intense green reflex from the ocular interior, visible through the developing pupillary aperture (B). The retina from a transgenic adult shows a mosaic pattern of GFP expression in the mature structure (C). Cultures from tissue taken at 60 days gestational age show GFP+ cells with characteristic morphology derived from the retina (D), forebrain (E), and corneo-scleral limbus (F). Photograph in (A) courtesy of Max Aguilera-Hellweg, photograph in (B) courtesy Kristin Whitworth. (See paper online for Fig. 1 in color.)