Circumventricular Mesencephalic Trigeminal Midline Ridge Formation in Cartilaginous Fishes: Species Variations
作者:
Malcolm F. MacDonnell,
期刊:
Brain, Behavior and Evolution
(Karger Available online 1984)
卷期:
Volume 24,
issue 2-3
页码: 124-134
ISSN:0006-8977
年代: 1984
DOI:10.1159/000121310
出版商: S. Karger AG
关键词: Mesencephalic trigeminal nucleus;Circumventricular organ;Sharks;Skates;Rays;Species variations
数据来源: Karger
摘要:
The midline ridge formation (MRF) of the trigeminal complex in 127 cartilaginous fish of 15 species was examined by scanning electron microscopy or light microscopy. Five distinct species variations of the MRF in sharks are described. The formation has not yet been observed to be present in skates and rays, but its presence in the subclass Holocephali, the sister group to the Elasmobranchii, indicates that this proposed circumventricular organ is an ancient brain characteristic of this line of vertebrates, perhaps predating the emergence of the class Chondrichthyii. The different types of MRF are compared to a current phyletic organization of the elasmobranchs and the possible functional significance of the formation is discussed briefly.
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