I've successfully used Biocytin tracing in 200 micron slices without
resectioning. I had 0.5% Neurobiotin (Vector Labs) in my pipette
soultion. After recording I carefully removed the pipette from the cell,
making sure not to destroy the cell. The slice was then transferred
immediately to a 0.4% paraformaldehyd solution and "incubated" at 4°C
for several days. The rest was "by the book" staining.
Hope that is of some help,