FIG. 4.

Transplantation and integration of GFP-transgenic progenitors in the eye. Following transplantation, spherical aggregates could be seen in the vitreous cavity, shown here for brain-derived cells and viewed both without back-illumination (A) and with the fundus in the background (B). Preretinal aggregates were confirmed histologically as GFP+ spheres (C). GFP+ spheres adhered to the vitreal surface of the retina, resulting in migration of GFP+ profiles into the host tissue and elaboration of fine processes (D–F). Retinal-derived donor cells survived in the subretinal space (G, arrowheads) and integrated into the RPE layer (H) as well as the neural retina (I–N). Integrating cells frequently displayed a radial orientation, seen here as vertical (I, arrows; J, arrowhead; K, arrowhead), and extended processes within the plexiform layers, especially the IPL (J,K). GFP+ profiles showed a tropism for areas of injury (L, arrows), including that produced by laser photocoagulation (L, centered on arrowhead), with asterisks indicating retinal lacunae peripheral to the central axis of the laser-induced damage (L). Individual profiles within the INL displayed both radial and horizontal orientations (M,N). (See paper online for Fig. 4 in color.)