Katzman R, Broida R, Raine C S
Brain Res. 1977 Dec 23;138(3):423-43. doi: 10.1016/0006-8993(77)90682-5.
The ultrastructure of autologous irides implanted into the midbrain of mature Sprague-Dawley rats was studied over a time period of 4-14 days. Most features of the normal iris still persisted throughout this time, including typical iris blood vessels and amelanotic melanocytes. At 5-4 days after implantation, the normal innervation of the implanted iris had degenerated, except for the presence of intact Schwann cells and some myelin debris. Reinnervation, beginning about the seventh day, proceeded rapidly. By the fourteenth day, extensive reinnervation of the implant was evidenced by the presence of numerous small (0.1-0.6 micrometer) and large (2-4 micrometer) non-myelinated axons ensheathed in Schwann cell cytoplasm. Axonal varicosities, filled either with dense core or clear core vesicles, formed junctions with axons. These junctions were characterized by an accentuation of areas of the axonal membrane and pre- or post-junctional thickenings; however, we did not observe typical synaptic complexes. Some large axons within the myelinated iris developed thick myelin sheaths of the peripheral nervous system (PNS) type; we believe this is the first reported instance in which myelination of central axons by Schwann cells within the brain parenchyma has been produced by the implantation of PNS elements.
在4至14天的时间段内，对植入成熟Sprague-Dawley大鼠中脑的自体虹膜超微结构进行了研究。在此期间，正常虹膜的大多数特征仍然存在，包括典型的虹膜血管和无色素黑素细胞。植入后4至5天，植入虹膜的正常神经支配已经退化，除了完整的施万细胞和一些髓鞘碎片的存在。大约从第七天开始的再支配迅速进行。到第十四天，植入物广泛的再支配表现为在施万细胞胞质内包裹着许多小的（0.1至0.6微米）和大的（2至4微米）无髓轴突。充满致密核心或清亮核心囊泡的轴突膨体与轴突形成连接。这些连接的特征是轴突膜区域的突出以及连接前或连接后的增厚；然而，我们没有观察到典型的突触复合体。有髓虹膜内的一些大轴突形成了外周神经系统（PNS）类型的厚髓鞘；我们认为这是首次报道的通过植入PNS元件在脑实质内由施万细胞对中枢轴突进行髓鞘化的实例。
