Pritz M B
Section of Neurological Surgery, Indiana University School of Medicine, Indianapolis 46202-5124, USA.
Brain Behav Evol. 1996;47(3):138-48. doi: 10.1159/000113233.
Interconnections between the dorsal column nucleus and the spinal cord were investigated in a reptile, Caiman crocodilus. After placement of an anterograde tracer into the dorsal column nucleus, descending fibers are seen to leave this nucleus to enter the dorsal funiculus where they course ventrally to terminate in lamina V of the spinal cord as far caudally as C2. Placement of a retrograde tracer into cut fibers of the cervical spinal cord identified the relay cells of the dorsal column nucleus that project to the spinal cord. These neurons were mainly clustered in a caudal and ventral part of this nucleus. The soma of these spinally projecting cells were small and were generally round or oval in shape. A number of these neurons had the long axis of their soma oriented dorsoventrally, with a primary dendrite extending dorsally. Fibers in the dorsal funiculus that originated from the spinal cord enter the caudal part of the dorsal column nucleus and turn ventral. In the dorsal column nucleus, these axons run parallel to the vertically oriented dendrites of these spinally projecting cells before termination in close relation to the cell bodies of these neurons. Quantitative observations (mean +/- standard error) were made on well labeled neurons and included several measurements: area, perimeter, and degree of eccentricity (greatest width/greatest length) in both the transverse as well as the sagittal plane. These spinally projecting neurons in Caiman are located in the dorsal column nucleus in a position similar to that of spinally projecting cells in cats.
在一种爬行动物——凯门鳄中，研究了背柱核与脊髓之间的联系。将一种顺行示踪剂注入背柱核后，可见下行纤维离开该核进入背侧索，在背侧索中它们向腹侧走行，终止于脊髓的V层，尾端可达C2水平。将逆行示踪剂注入颈段脊髓的切断纤维中，确定了背柱核中投射到脊髓的中继细胞。这些神经元主要聚集在该核的尾侧和腹侧部分。这些投射到脊髓的细胞的胞体较小，通常呈圆形或椭圆形。其中许多神经元的胞体长轴呈背腹方向，有一条初级树突向背侧延伸。起源于脊髓的背侧索纤维进入背柱核的尾侧部分并转向腹侧。在背柱核中，这些轴突在与这些投射到脊髓的细胞的树突垂直排列的方向上平行走行，然后终止于与这些神经元的胞体紧密相关的位置。对标记良好的神经元进行了定量观察（平均值±标准误差），包括多项测量：在横切面和矢状面中的面积、周长和偏心率（最大宽度/最大长度）。凯门鳄中这些投射到脊髓的神经元位于背柱核中的位置与猫中投射到脊髓的细胞的位置相似。
