Seyama S, Pearl G S, Takei Y
Cell Tissue Res. 1980;205(2):253-71. doi: 10.1007/BF00234684.
Neurosecretory axons and their dilatations in the pars nervosa of the human neurohypophysis were studied electron microscopically. The axons are of two different types based on their content of neurosecretory granules (NSGs): (i) NSGs of Type A are 100-300 nm, and (ii) NSGs of type B are 50-100 nm in diameter. While fibers (or axons) of type B were scarce, showing simple swellings and terminal formations, fibers of type A were ubiquitous in the human pars nervosa, exhibiting numerous dilatations with a diversity of internal structure, apparently representing the ultrastructural manifestation of intraaxonal turnover of neurohypophysial hormones. Based on the predominating aspect of their internal structure, dilatations of type A-fibers were classified into six different types, with various transitional forms: Type I is characterized by abundant NSGs; type II by prominent mitochondria; type III by abundant lysosomal bodies; type IV by an electron-lucent matrix with few organelles; type V by prominent tubuloreticular profiles; and type VI by numerous microvesicles. The functional significance of each type is discussed and a scheme of possible interrelationships between these dilatations is proposed.
对人类神经垂体神经部的神经分泌轴突及其膨大部进行了电子显微镜研究。根据神经分泌颗粒（NSGs）的含量，轴突有两种不同类型：（i）A型神经分泌颗粒直径为100 - 300纳米，（ii）B型神经分泌颗粒直径为50 - 100纳米。B型纤维（或轴突）稀少，表现为简单的肿胀和终末结构，而A型纤维在人类神经垂体神经部普遍存在，呈现出许多具有多样内部结构的膨大部，显然代表了神经垂体激素轴突内周转的超微结构表现。根据其内部结构的主要特征，A型纤维的膨大部被分为六种不同类型，伴有各种过渡形式：I型的特征是有丰富的神经分泌颗粒；II型以突出的线粒体为特征；III型以丰富的溶酶体为特征；IV型以电子透明的基质且细胞器较少为特征；V型以突出的管状网状结构为特征；VI型以众多微泡为特征。讨论了每种类型的功能意义，并提出了这些膨大部之间可能的相互关系图。
