mESCs maintain pluripotency after coculture with dermal cells. (a) Networks of neurons extend from EBs derived from mESCs after 6-day coculture with PVG rat DS cells. (b) GFP mESCs after 6-day coculture with PVG DP cells produce neuron-like cells; the projections of which are visible by fluorescence microscopy. Immunostaining with anti-NF200 antibodies demonstrates expression of neurofilament (red) and the colocalization with the GFP fluorescence (green). (c) ESCs cocultured with PVG DS for 6 days produced high levels of lipid (red). One EB in particular was observed to be producing copious amounts of lipid. Endodermal cells are present in differentiated cells from 6-day cocultures of GFP mESCs with PVG DP (d) and Z40 DP (e). Green fluorescence identifies the cells as being of mESC origin while red fluorescence shows immunoreactivity for albumin (d) and AFP (e). Scale bars (a) = 200 μm, (b–e) = 50 μm, and (d) = 25 μm.