Bindler E, Labella F S, Sanwal M
J Cell Biol. 1967 Jul;34(1):185-205. doi: 10.1083/jcb.34.1.185.
Subcellular fractions of the bovine posterior pituitary, including one composed almost exclusively of pinched-off nerve endings (neurosecretosomes), were characterized electron microscopically, hormonally, and enzymically. 15% of the nerve terminals in the gland were isolated as neurosecretosomes, as estimated from determinations of lactic dehydrogenase, a soluble, cytoplasmic enzyme. Neurosecretosomes were subdivided into three fractions by density-gradient centrifugation. The three subfractions, each shown to be nearly homogeneous populations of neurosecretosomes by means of electron microscopic and enzymic criteria, differed from each other in their vasopressin/oxytocin (VP/OT) ratios. The VP/OT ratio increased from the lightest to the densest fraction, indicating that VP is localized to denser and OT to lighter neurosecretosomes; similar results have been obtained previously for subfractions of neurosecretory granules (NSG). No morphological differences were apparent in neurosecretosomes among the three subfractions. Although complete separation of VP and OT was not achieved, the findings suggest that VP and OT are each stored in a different species of nerve ending and support the hypothesis that a given neurosecretory cell synthesizes, stores, and secretes only one of the peptide hormones. Microvesicles, 40-80 mmicro diameter and contained in typical neurosecretory cell terminals, are believed to be degradation products of membrane ghosts of depleted NSG; electron micrographs indicative of this transformation are presented. A fraction rich in microvesicles, but containing some NSG membranes, was prepared by density-gradient centrifugation of an osmolysate of neurosecretosomes. Smaller, apparently nonneurosecretory nerve endings, lacking NSG but filled with small vesicles, are occasionally seen in sections from whole gland. The vesicles in these atypical posterior pituitary nerve endings may be true neurohumor-containing, "synaptic" vesicles.
对牛脑垂体后叶的亚细胞组分进行了电子显微镜、激素和酶学特性分析。其中一个组分几乎完全由缢断的神经末梢（神经分泌小体）组成。根据乳酸脱氢酶（一种可溶性细胞质酶）的测定估计，腺体中15%的神经末梢被分离为神经分泌小体。通过密度梯度离心将神经分泌小体细分为三个组分。根据电子显微镜和酶学标准，这三个亚组分中的每一个都显示为几乎均一的神经分泌小体群体，它们的血管加压素/催产素（VP/OT）比值彼此不同。VP/OT比值从最轻的组分到最重的组分逐渐增加，表明VP定位于密度较大的神经分泌小体，而OT定位于密度较小的神经分泌小体；先前对神经分泌颗粒（NSG）亚组分也获得了类似结果。在这三个亚组分的神经分泌小体之间没有明显的形态学差异。尽管没有实现VP和OT的完全分离，但这些发现表明VP和OT分别储存在不同种类的神经末梢中，支持了给定的神经分泌细胞仅合成、储存和分泌一种肽类激素的假说。微泡直径为40 - 80微米，存在于典型的神经分泌细胞终末中，被认为是耗尽的NSG膜鬼的降解产物；文中给出了表明这种转变的电子显微照片。通过对神经分泌小体渗透压裂解物进行密度梯度离心，制备了一个富含微泡但含有一些NSG膜的组分。在整个腺体的切片中偶尔可以看到较小的、明显非神经分泌的神经末梢，它们缺乏NSG但充满小泡。这些非典型脑垂体后叶神经末梢中的小泡可能是真正含有神经体液的“突触”小泡。
