Theodosis D T, Dreifuss J, Harris M C, Orci L
J Cell Biol. 1976 Aug;70(2 pt 1):294-303. doi: 10.1083/jcb.70.2.294.
During secretion of the neurohypophysial hormones, oxytocin and vasopressin, secretory granule membrane is added to the plasma membrane of the axon terminals. It is generally assumed that subsequent internalization of this additional membrane occurs by endocytosis. In order to study this process, we have traced the uptake of intravenously injected horseradish peroxidase by neurohypophysial axons in rats and golden hamsters. Peroxidase reaction product within the secretory axons was found mainly in vacuolar and C-shaped structures of a size comparable with or larger than the neurosecretory granules. Our observations suggest that these large horseradish peroxidase (HRP)-impregnated vacuoles arise directly by a form of macropinocytosis. Morphometric analysis indicated that this form of membrane retrieval increased significantly after the two types of stimuli used, reversible hemorrhage and electrical stimulation of the pituitary stalk. Microvesicular uptake of HRP was found to be comparatively less.
在神经垂体激素（催产素和血管加压素）分泌过程中，分泌颗粒膜会添加到轴突终末的质膜上。一般认为，随后这种额外膜的内化是通过内吞作用发生的。为了研究这个过程，我们追踪了大鼠和金黄仓鼠神经垂体轴突对静脉注射辣根过氧化物酶的摄取情况。分泌轴突内的过氧化物酶反应产物主要存在于与神经分泌颗粒大小相当或更大的泡状和C形结构中。我们的观察结果表明，这些被大量辣根过氧化物酶（HRP）浸染的液泡直接通过一种巨胞饮作用形式产生。形态计量分析表明，在使用的两种刺激（可逆性出血和垂体柄电刺激）后，这种膜回收形式显著增加。发现HRP的微泡摄取相对较少。
