Chandler D E, Heuser J E
J Cell Biol. 1980 Aug;86(2):666-74. doi: 10.1083/jcb.86.2.666.
We have used quick-freezing and freeze-fracture to study early stages of exocytosis in rat peritoneal mast cells. Mast cells briefly stimulated with 48/80 (a synthetic polycation and well-known histamine-releasing agent) at 22 degrees C displayed single, narrow-necked pores (some as small as 0.05 micrometer in diameter) joining single granules with the plasma membrane. Pores that had become as large as 0.1 micrometer in diameter were clearly etchable and thus represented aqueous channels connecting the granule interior with the extracellular space. Granules exhibiting pores usually did not have wide areas of contact with the plasma membrane, and clearings of intramembrane particles, seen in chemically fixed mast cells undergoing exocytosis, were not present on either plasma or granule membranes. Fusion of interior granules later in the secretory process also appeared to involve pores; granules were often joined by one pore or a group of 2-4 pores. Also found were groups of extremely small, etchable pores on granule membranes that may represent the earliest aqueous communication between fusing granules.
我们利用快速冷冻和冷冻断裂技术研究大鼠腹膜肥大细胞胞吐作用的早期阶段。在22摄氏度下，用48/80（一种合成聚阳离子和著名的组胺释放剂）短暂刺激的肥大细胞显示出单个狭窄颈部的孔（有些直径小至0.05微米），将单个颗粒与质膜相连。直径达0.1微米的孔明显可蚀刻，因此代表连接颗粒内部与细胞外空间的水通道。显示有孔的颗粒通常与质膜没有大面积接触，在经历胞吐作用的化学固定肥大细胞中看到的膜内颗粒清除现象，在质膜或颗粒膜上均未出现。分泌过程后期内部颗粒的融合似乎也涉及孔；颗粒通常通过一个孔或一组2 - 4个孔相连。在颗粒膜上还发现了极微小的可蚀刻孔群，这可能代表融合颗粒之间最早的水通道连接。
