Dunn R C, Westrum L E
Brain Res. 1978 Mar 31;143(3):421-36. doi: 10.1016/0006-8993(78)90354-2.
Pars interpolaris of the spinal trigeminal nucleus of kittens has been studied with the electron microscope at birth and at several subsequent ages during the first month of life. Attention has been given to ultrastructural maturational changes that occur in this neuropil, especially events in synaptogenesis. The results of this investigation include the following observations: (1) the neuropil, even at the earliest ages studied (three-hour-old kittens), is strikingly mature, necessitating a quantitative assessment in order to determine subtle developmental changes in synaptic patterns; (2) the number of axoaxonic contacts at birth are few, and their emergence is essentially a postnatal phenomenon; (3) it appears that the immature Gray type II or symmetrical synapse possesses distinct cleft material and dense, parallel membrane specializations. Synaptic vesicle accumulation at this contact appears to occur after the membrane specializations have formed. A previous study by Kerr26 has shown a reduced potential for primary afferent reorganization with the spinal trigeminal nucleus when kittens are subjected to trigeminal rhizotomy after three days of age. Our observations on the development of axoaxonic synaptic arrangements in the neonatal period may provide an explanation for these earlier results.
利用电子显微镜对新生小猫以及出生后第一个月内几个后续年龄段小猫的三叉神经脊束核极间部进行了研究。研究重点关注了该神经纤维网中发生的超微结构成熟变化，尤其是突触发生过程中的事件。本次调查结果包括以下观察结果：（1）即使在最早研究的年龄（出生3小时的小猫），神经纤维网也已显著成熟，因此需要进行定量评估以确定突触模式中细微的发育变化；（2）出生时轴-轴突触接触数量很少，其出现本质上是一种出生后现象；（3）似乎未成熟的II型灰质或对称突触具有独特的突触间隙物质和密集、平行的膜特化结构。在这种接触处突触小泡的积累似乎发生在膜特化结构形成之后。克尔之前的一项研究表明，小猫在3日龄后接受三叉神经根切断术时，三叉神经脊束核初级传入纤维重组的可能性降低。我们对新生儿期轴-轴突触排列发育的观察结果可能为这些早期结果提供解释。
