Cell culture reagents were obtained from GIBCO (Grand Island, NY).
The retrograde fluorescent tracers
1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine
(DiIC18) and
1,1′-dihexdecyl-3,3,3′,3′-tetramethylindocarbocyanine
(DiIC16), and the fluorescent viability agent
calcein-AM were obtained from Molecular Probes (Eugene, OR). Papain was
obtained from Worthington Biochemical (Freehold, NJ). Unless noted, all
other reagents were obtained from Sigma (St. Louis, MO).