Figure 5
Quantification of noradrenergic bouton density in cetartiodactyl cerebral cortex. Photomicrographs of dopamine-ß-hydroxylase (DBH)-immunostained axonal boutons in the occipital cortical grey matter of Camelus dromedarius, Hippopotamus amphibius, and Phocoena phocoena, and the anterior cingulate cortical grey matter of Balaenoptera acutorostrata. The scale bar = 50 µm and applies to all photomicrographs. Note the higher density of the DBH-immunoreactive boutons in the cortical grey matter of cetaceans compared to the artiodactyls as confirmed with stereological analysis (see the graph below the photomicrographs), showing that the density of DBH-immunoreactive boutons in the cortical grey matter of cetaceans is, on average, 1.4 times higher than that observed in artiodactyls (Table 1, error bars on average bars represent one standard deviation). Gm—sand gazelle, Gazella marica; Ss—domestic pig, Sus scrofa; Cn—Nubian ibex, Capra nubiana; Am—springbok, Antidorcas marsupialis; Dp—blesbok, Damaliscus pygargus; Ts—greater kudu, Tragelaphus strepsiceros; Ct—blue wildebeest, Connochaetes taurinus; Cd—dromedary camel, Camelus dromedarius; Ta—nyala, Tragelaphus angasii; Ha—river hippopotamus, Hippopotamus amphibius; Sc—African buffalo, Syncerus caffer; av. —average; Pp—harbor porpoise, Phocoena phocoena; Ba—minke whale, Balaenoptera acutorostrata.
