Zeng B Y, Anderson P N, Campbell G, Lieberman A R
Department of Anatomy and Developmental Biology, University College London, UK.
J Anat. 1994 Dec;185 ( Pt 3)(Pt 3):643-61.
The proximal stump of the optic nerve was examined by electron microscopy from 1 d to 8 wk (dpo/wpo) after intraorbital transection. At 1 dpo a layer of axonal, cytoplasmic and myelin debris approximately 15 microns thick was present at the cut end. A zone approximately 25 microns thick of abnormal and partly degenerate tissue composed of many swollen axons filled with organelles of predominantly abnormal appearance lay between the zone of debris and more proximal levels of the optic nerve, which retained a normal appearance. The earliest putative axonal sprouts were seen at 1 dpo in this zone. By 2 dpo, bundles of small nonmyelinated axons containing microtubules, almost certainly axonal sprouts, had grown out from more proximal regions of the proximal stump and extended as far as its cut end. By 3 dpo, large numbers of axonal sprouts, as well as large numbers of macrophages and newly formed blood vessels, were seen close to the cut end of the proximal stump. Glial cells were not seen to accompany these early outgrowing bundles of axonal sprouts. By 5 dpo, the number of sprouts and macrophages had increased; many bundles of sprouts were now in contact with the surface of astrocytes, which were partly covered by basal lamina. At 7 dpo most of the macrophages had disappeared from the most distal part of proximal stump and bundles of axonal sprouts, associated with astrocytes, which in some cases had penetrated and were fasciculating such bundles, were present at the cut end. The regenerating axonal sprouts in the scar-like tissue at the distal end of the proximal stump of the optic nerve declined in numbers sharply at 2 wpo and only a few sprout-like axonal profiles were present by 8 wpo. Thus while ultimately abortive the early regenerative response is vigorous and involves the outgrowth of a large number of axonal sprouts in the first week after injury.
眶内横断视神经后1天至8周（术后天数/周数），通过电子显微镜检查视神经近端残端。术后1天，在切断端有一层约15微米厚的轴突、细胞质和髓鞘碎片。在碎片区和视神经更近端外观正常的区域之间，有一个约25微米厚的异常且部分退化的组织区，该区域由许多充满主要外观异常细胞器的肿胀轴突组成。最早的假定轴突芽在术后1天出现在该区域。到术后2天，含有微管的小无髓鞘轴突束，几乎可以肯定是轴突芽，已从近端残端的更近端区域长出，并延伸至其切断端。到术后3天，在近端残端切断端附近可见大量轴突芽，以及大量巨噬细胞和新形成的血管。未见神经胶质细胞伴随这些早期长出的轴突芽束。到术后5天，芽和巨噬细胞数量增加；许多芽束现在与星形胶质细胞表面接触，星形胶质细胞部分被基膜覆盖。术后7天，大多数巨噬细胞已从近端残端最远端和轴突芽束中消失，与星形胶质细胞相关的轴突芽束出现在切断端，在某些情况下，星形胶质细胞已穿透并束化这些芽束。视神经近端残端远端瘢痕样组织中的再生轴突芽在术后2周时数量急剧下降，到术后8周时仅存在少数芽样轴突轮廓。因此，虽然早期再生反应最终失败，但在损伤后的第一周内反应强烈，涉及大量轴突芽的长出。
