Anatomic markers of DMH borders (dashed lines) in Nissl-stained coronal sections (A) and after in situ hybridization for TRH mRNA (B). Retrograde tracer injections into the VLPO also label many DMH neurons (C). D-F show these same markers at a caudal DMH level where the pars compacta (solid outline) is apparent. Scale bars, 200 μm.