Zelená J, Jirmanová I
Institute of Physiology, Academy of Sciences of the Czech Republic, Prague.
J Neurocytol. 1995 Dec;24(12):955-64. doi: 10.1007/BF01215645.
The ultrastructure of crural Pacinian corpuscles was examined after sciatic nerve crush performed in 7- to 20-day-old rats, i.e. during the postcritical period of development when the corpuscles no longer degenerate after axotomy but cease growing. The aim of our study was to assess the innervation pattern and structural changes of the corpuscles following transient denervation and subsequent reinnervation during their maturation and growth. Reinnervated corpuscles were examined by electron microscopy from 2.5 months after nerve crush onwards. After sciatic nerve crush at 7 days of age, the corpuscles are mostly reinnervated with multiple axon terminals, each of them enclosed within a newly formed inner core. The axial multiple cores are in part covered by a layer of concentric inner core lamellae and surrounded by a capsule, both structures having survived from the original corpuscle. After nerve crush at 10 days of age, reinnervated Pacinian corpuscles usually contain, in their axial region, a denervated remainder of the original core together with a few regenerated axon terminals enclosed within new inner cores. These axial structures are surrounded by a layer of concentric lamellae of the original core which may accommodate some regenerated terminals. Additional axon terminals with their small inner cores may be found at the outer aspect of the composite core beneath the capsule. When the nerve is crushed in 15-day-old rats, the inner core which is already well developed remains preserved by the time of reinnervation, and regenerating axons grow in between the original lamellae inducing only moderate neoformation of 2-3 lamellar layers which enclose the terminals. After crushing the sciatic nerve in 20-day-old rats, formation of new inner core lamellae is minimal and regenerated terminals become accommodated between the original lamellar of the core as is the case in adult animals. Regeneration of new inner cores and reinnervation of the preserved lamellar structure thus characterize the recovery of Pacinian corpuscles following reinnervation after nerve crush during the postcritical period of their development.
在7至20日龄大鼠中进行坐骨神经挤压后，对小腿环层小体的超微结构进行了检查，即处于发育的关键期之后，此时小体在轴突切断后不再退化，但停止生长。我们研究的目的是评估在小体成熟和生长过程中，短暂去神经支配及随后再支配后小体的神经支配模式和结构变化。从神经挤压后2.5个月起，通过电子显微镜检查再支配的小体。7日龄时进行坐骨神经挤压后，小体大多由多个轴突终末再支配，每个轴突终末被包裹在新形成的内核内。轴向的多个内核部分被一层同心的内核板层覆盖，并被一个被膜包围，这两种结构都从原始小体保留下来。10日龄时神经挤压后，再支配的环层小体在其轴向区域通常含有原始内核的失神经剩余部分，以及一些包裹在新内核内的再生轴突终末。这些轴向结构被一层原始内核的同心板层包围，该板层可容纳一些再生终末。在复合内核的外侧、被膜下方可能会发现带有小内核的额外轴突终末。当在15日龄大鼠中挤压神经时，再支配时已经发育良好的内核得以保留，再生轴突在原始板层之间生长，仅诱导形成2 - 3个包围终末的板层层的适度新形成。在20日龄大鼠中挤压坐骨神经后，新内核板层的形成极少，再生终末像成年动物那样被容纳在核心的原始板层之间。因此，新内核的再生和保留板层结构的再支配是环层小体在其发育关键期神经挤压后再支配后恢复的特征。
