1 40 1 Text A resource consisting primarily of words for reading. Examples include books, letters, dissertations, poems, newspapers, articles, archives of mailing lists. Note that facsimiles or images of texts are still of the genre Text. URL Address <a href="http://doi.org/10.1159/000114106" target="_blank" rel="noreferrer noopener">http://doi.org/10.1159/000114106</a> Pages 77–92 Issue 2 Volume 39 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Distribution of tyrosine hydroxylase, serotonin, and leu-enkephalin immunoreactive cells in the brainstem of a shark, Squalus acanthias. Publisher An entity responsible for making the resource available Brain, behavior and evolution Date A point or period of time associated with an event in the lifecycle of the resource 1992 1992 Subject The topic of the resource Animals; Brain Mapping; Brain Stem/*anatomy & histology; Diencephalon/anatomy & histology; Dogfish/*anatomy & histology; Enkephalin; Immunoenzyme Techniques; Leucine/*analysis; Mesencephalon/anatomy & histology; Nerve Fibers/ultrastructure; Neurons/ultrastructure; Rhombencephalon/anatomy & histology; Serotonin/*analysis; Spinal Cord/anatomy & histology; Tyrosine 3-Monooxygenase/*analysis Creator An entity primarily responsible for making the resource Stuesse S L; Cruce W L Description An account of the resource The central nervous system location of neurochemicals that are widely distributed among extant animals may give us clues to changes that occurred in the brains of these animals during evolution. We have been studying the brains of cartilaginous fishes, a heterogeneous group whose central nervous system varies considerably. Squalus acanthias, the spiny dogfish shark, was chosen to represent the squalomorphs, a group of living sharks known to possess many primitive characters. The distribution of tyrosine hydroxylase (TH+), serotonin (5-HT+), and leu-enkephalin (LENK+) positive cells within the brainstem of Squalus was determined by use of antibodies to these substances. All the major raphe groups described for mammals were found in Squalus. The 5-HT+ cells in raphe nuclei were more uniformly distributed in Squalus than in Heterodontus, the horn shark. Other nuclei that were 5-HT+ and LENK+, and that have been identified in mammals, included reticularis paragigantocellularis lateralis, a B9 cell group, and reticularis magnocellularis. The postcommissural nucleus and pretectal area contained 5-HT+ and LENK+ cells. These cells have been described in a holocephalian, in teleosts, and in reptiles but not in other elasmobranchs or in mammals. Cells that were TH+ were located in prominent A1/A2, A6 (locus coeruleus), A9 (substantia nigra), and A10 (ventral tegmental area) cell groups, and in a very small A5 group. We conclude that the variation in chondrichthian brainstems exceeds that in mammals, and we suggest that this variation is related to life-style and the long evolutionary history of these fishes. Identifier An unambiguous reference to the resource within a given context <a href="http://doi.org/10.1159/000114106" target="_blank" rel="noreferrer noopener">10.1159/000114106</a> Rights Information about rights held in and over the resource Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s). 1992 Animals Brain Mapping Brain Stem/*anatomy & histology Brain, behavior and evolution Cruce W L Diencephalon/anatomy & histology Dogfish/*anatomy & histology Enkephalin Immunoenzyme Techniques Leucine/*analysis Mesencephalon/anatomy & histology Nerve Fibers/ultrastructure Neurons/ultrastructure Rhombencephalon/anatomy & histology Serotonin/*analysis Spinal Cord/anatomy & histology Stuesse S L Tyrosine 3-Monooxygenase/*analysis