Lane N J, Leslie R A, Swales L S
J Cell Sci. 1975 Jun;18(1):179-97. doi: 10.1242/jcs.18.1.179.
During incubation in vivo, exogenously applied ionic lanthanum comes to surround the numerous neurosecretory terminals which are found lying within or immediately beneath the acellular neural lamella ensheathing the nerves from fifth instar and adult specimens of Rhodnius prolixus. The lanthanum does not penetrate beyond the cellular perineurium, which completely surrounds the non-neurosecretory axons in these nerves and constitutes a form of 'blood-brain barrier'. In some cases, however, lanthanum is found in the vicinity of a neurosecretory axon lying beneath the perineurium, where it can be assumed to have leaked in from the neurosecretory terminal lying free in the neural lamella. When nerves are incubated in calcium-free media, regions with an attenuated perineurium become 'leaky', in that lanthanum is found lying in those extracellular spaces between axons and glia which lie immediately below the thin part of the perineurial layer. Bathing solutions made slightly hyperosmotic to the haemolymph with sucrose have no apparent disruptive effects on the barrier. When the tissues are incubated in more hypertonic solutions, the perineurial barrier becomes 'leaky' throughout, and tracer pervades beyond its cells into all the intercellular spaced between glia and axons. The possible role of the zonulae occludentes in both the maintenance of the perineurial barrier and in the formation of interglial occlusions to local penetration of exogenous substances is considered.
在体内孵育过程中，外源性施加的离子镧会包围众多神经分泌终末，这些终末位于无细胞神经片层内或其紧邻下方，该神经片层包裹着来自五龄若虫和成年南美锥蝽标本的神经。镧不会穿透细胞性神经周膜，神经周膜完全包围这些神经中的非神经分泌轴突，构成一种“血脑屏障”形式。然而，在某些情况下，在神经周膜下方的神经分泌轴突附近发现有镧，推测它是从位于神经片层中的游离神经分泌终末渗漏进来的。当神经在无钙培养基中孵育时，神经周膜变薄的区域会变得“渗漏”，因为在轴突和神经胶质细胞之间紧邻神经周膜层薄部分下方的细胞外间隙中发现有镧。用蔗糖使浴液渗透压略高于血淋巴对屏障没有明显的破坏作用。当组织在更高渗的溶液中孵育时，神经周膜屏障会整体变得“渗漏”，示踪剂会穿过其细胞扩散到神经胶质细胞和轴突之间的所有细胞间隙中。本文考虑了紧密连接在维持神经周膜屏障以及形成神经胶质细胞间封闭以阻止外源性物质局部渗透方面的可能作用。
