Photomicrographs showing the relationships of anterogradely labeled efferent axons (black) from the extended VLPO and VLPO cluster with neurons in the DRN, LDT, and LC that are stained (brown) for serotonin, choline acetyltransferase, or tyrosine hydroxylase, respectively. InA, the efferent terminals concentrate dorsal to the cluster of the cholinergic cells in the LDT. Occasionally we found that terminal boutons were near choline acetyltransferase-immunoreactive neurons such as in B; however careful observation indicated that such boutons were not on the same plane as the cholinergic cell body. In C and D, efferent terminal boutons clearly appose serotonin-immunoreactive neurons in the DRN. E and F show labeled efferent axons apposing tyrosine hydroxylase-immunoreactive neurons in the LC.