Schroeder D M, Murray R G
Medical Sciences Program, Indiana University School of Medicine, Bloomington, Indiana 47405.
J Morphol. 1987 Oct;194(1):41-53. doi: 10.1002/jmor.1051940104.
The prominent accessory lobes of Lachi in birds are considered to be marginal nuclei; similar nuclei have been implicated in mechanoreceptive functions in snakes and lampreys. Reptile studies emphasized the involvement of the denticulate ligament with this mechanoreceptive function. This investigation examines the fine structure of the accessory lobes of Lachi in pigeons and their interaction with ligaments for features which might support such a mechanoreceptive function. In the lumbosacral area of the spinal cord, the lateral longitudinal ligaments and the ventral longitudinal ligament are hypertrophied. The ventral transverse ligaments are present only within the lumbosacral segments of the spinal cord and they interconnect with the lateral and ventral longitudinal ligaments. The lateral longitudinal ligament makes intimate contact with the spinal cord, and many glial processes from the spinal cord mingle with and are firmly attached to collagenous fibers of the ligament. The lobes lie dorsal to the lateral longitudinal ligament in the exact area where it interconnects with the transverse ligament. The lobe's multipolar neurons have a number of synaptic contacts but no unusual specializations were noted. Most of each lobe is composed of interdigitating saccular structures filled to varying degrees with flocculent material. The sacs are extensions of the cytoplasm of neuroglial cells, which also give rise to membranes surrounding neuronal processes and the sacs themselves. A possible functional relationship of the lobes and the ligaments of the lumbosacral spinal segments within the vertebral column is described.
鸟类中突出的拉氏副叶被认为是边缘核；类似的核在蛇和七鳃鳗的机械感受功能中也有涉及。爬行动物研究强调了齿状韧带与这种机械感受功能的关联。本研究考察了鸽子拉氏副叶的精细结构及其与韧带的相互作用，以寻找可能支持这种机械感受功能的特征。在脊髓的腰骶区域，外侧纵韧带和腹侧纵韧带肥厚。腹侧横韧带仅存在于脊髓的腰骶节段内，它们与外侧纵韧带和腹侧纵韧带相互连接。外侧纵韧带与脊髓紧密接触，脊髓的许多胶质突起与韧带的胶原纤维混合并牢固附着。这些叶位于外侧纵韧带与横韧带相连的确切区域的背侧。叶内的多极神经元有许多突触联系，但未发现异常特化。每个叶的大部分由相互交错的囊状结构组成，这些结构不同程度地充满了絮状物质。这些囊是神经胶质细胞细胞质的延伸，神经胶质细胞还产生围绕神经元突起和囊本身的膜。描述了脊柱内腰骶脊髓节段叶与韧带之间可能的功能关系。
