MacDonnell M F
Brain Behav Evol. 1984;24(2-3):124-34. doi: 10.1159/000121310.
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.
通过扫描电子显微镜或光学显微镜对15种127条软骨鱼类三叉神经复合体的中线嵴形成（MRF）进行了检查。描述了鲨鱼中MRF的五种不同的物种变异。在鳐鱼和魟鱼中尚未观察到这种形成，但在板鳃亚纲的姐妹类全头亚纲中存在，这表明这种拟议的室周器官是这一脊椎动物谱系古老的脑特征，可能早于软骨鱼纲的出现。将不同类型的MRF与板鳃亚纲当前的系统发育组织进行了比较，并简要讨论了这种形成可能的功能意义。
