Figure 2. Mirror staining of the pars intercerebralis (PI) of Phormia regina. A) pars intercerebralis region of the protocerebrum stained with anti-FMRFamide antiserum using the peroxidase-antiperoxidase technique of Sternberger (1979). Arrows indicate large, medial FMRFamide-like immunoreactive (FLI) cells surrounded by smaller cells exhibiting little or no FLI. B). Adjacent paraffin section showing type-A median neurosecretory cells stained with paraldehyde fuchsin. Arrows indicate large, unstained medial cells corresponding to the FLI cells of the previous section. CB, central body.