  We present a new and versatile implementation of rapid and localized
immunohistochemical staining of tissue sections. Immunohistochemistry (IHC)
allows to detect specific proteins on tissue sections and comprises a sequence
of specific biochemical reactions. For the rapid implementation of IHC, we
fabricated horizontally oriented microfluidic probes (MFP) with functionally
designed apertures to enable square and circular footprints, which we employ to
locally expose a tissue to time-optimized sequences of different biochemicals.
