The Distribution and Morphological Characteristics of Catecholaminergic Cells in the Diencephalon and Midbrain of the Bottlenose Dolphin (Tursiops truncatus)Manger P.R.a,d · Fuxe K.b · Ridgway S.H.c · Siegel J.M.d
aSchool of Anatomical Sciences, Faculty of Health Science, University of the Witwatersrand, Johannesburg, Republic of South Africa; bDepartment of Neuroscience, Karolinska Institutet, Stockholm, Sweden; cUS Navy Marine Mammal Program, SSC, SD, San Diego, Calif., dDepartment of Psychiatry, University of California, Los Angeles, Neurobiology Research, North Hills, Calif., USA
The present study describes the distribution and cellular morphology of catecholaminergic neurons in the diencephalon and midbrain of the bottlenose dolphin (Tursiops truncatus). Tyrosine hydroxylase immunohistochemistry was used to visualize these putatively dopaminergic neurons. The standard A1-A17, C1-C3, nomenclature is used for expediency; however, the neuroanatomical names of the various nuclei have also been given. Dolphins exhibit certain tyrosine hydroxylase immunoreactive (TH-ir) catecholaminergic neuronal groups in the midbrain (A8, A9, A10) and diencephalon (A11, A12, A14), however, no neuronal clusters clearly corresponding to the A13 and A15 groups could be identified. The subdivisions of these neuronal groups are in general agreement with those of other mammals, but there is a high degree of species specificity. First, three TH-ir neuronal groups not identified in other species were found: in the ventral lateral peri-aqueductal gray matter, posterior dorsal hypothalamus, and rostral mesencephalic raphe. Second, the normal components of the substantia nigra (A9 or pars compacta, A9 lateral or pars lateralis, A9 ventral or pars reticulata) were extremely cell sparse, but there was a substantial expansion of the A9 medial and A10 lateral subdivisions forming an impressive ‘ventral wing’ in the posterior substantia nigra. The findings of this and previous studies suggest a distinct evolutionary trend occurring in the neuromodulatory systems in mammals. The results are discussed in relation to motor control, thermoregulation, unihemispheric sleep, and dolphin cognition.
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Received: September 3, 2003
Returned for revision: October 24, 2003
Accepted after revision: December 16, 2003
Published online: March 26, 2004
Number of Print Pages : 19
Number of Figures : 8, Number of Tables : 0, Number of References : 74
Brain, Behavior and Evolution
Founded 1968 and continued 1968–1986 by W. Riss, New York, N.Y.
Official Organ of the J.B. Johnston Club
Vol. 64, No. 1, Year 2004 (Cover Date: Released June 2004)
Journal Editor: Walter Wilczynski, Austin, Tex.
ISSN: 0006–8977 (print), 1421–9743 (Online)
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