Sommer U, Kressin M, Schnorr B
Department of Veterinary Anatomy, Histology and Embryology, University of Giessen, Germany.
Acta Anat (Basel). 1998;163(1):20-30. doi: 10.1159/000046442.
The fine structural distribution of cytoskeletal actin was investigated in the oxyntic gland region and in the pyloric gland region of bovine abomasal mucosa using immunoelectron methods. In all exocrine cell types of the gastric epithelium, actin filaments exhibit a polarized pattern of distribution. In the members of the mucus- and protein-synthesizing cell line, the actin filaments form a prominent barrier to the exocytosis of secretory granules underneath the apical membrane. Therefore, actin is supposed to be involved in the control of exocytosis. The basolateral subplasmalemmal cortex of the exocrine cells, however, shows weaker labeling for actin filaments. In this position actin might be responsible for the movement of epithelial cells along the length of the gastric gland during physiological cell renewal and for the maintenance of the integrity of the epithelial unit and of cell polarization. In parietal cells of bovine abomasum, actin filaments are, in addition, associated with the intracellular canaliculus, but not with the tubulovesicular compartment. We assume that actin filaments reorganize the canalicular membrane after membrane translocations in the course of acid secretion. For the first time, actin filaments were documented in the rare brush cell type of bovine abomasum, where they do not form a terminal web beneath the apical membrane and therefore point out the nonexocrine function of the brush cell type. In all polarized cells of the bovine abomasum, actin filaments underlay the two apical members of the junctional complex, the tight junction and the adherens junction, where they might be involved in the regulation of cell adhesion, cell motility and cell shape determination.
采用免疫电子方法研究了牛皱胃黏膜胃底腺区和幽门腺区细胞骨架肌动蛋白的精细结构分布。在胃上皮的所有外分泌细胞类型中，肌动蛋白丝呈现出极化分布模式。在黏液合成细胞系和蛋白质合成细胞系的成员中，肌动蛋白丝在顶膜下方形成了一道显著的屏障，阻止分泌颗粒的胞吐作用。因此，推测肌动蛋白参与了胞吐作用的调控。然而，外分泌细胞基底外侧的质膜下皮质区，肌动蛋白丝的标记较弱。在这个位置，肌动蛋白可能在生理性细胞更新过程中负责上皮细胞沿胃腺长度的移动，以及维持上皮单元的完整性和细胞极化。在牛皱胃的壁细胞中，肌动蛋白丝还与细胞内小管相关，但与微管泡系统无关。我们认为，在酸分泌过程中，膜移位后肌动蛋白丝会重新组织小管膜。首次在牛皱胃罕见的刷状细胞类型中记录到肌动蛋白丝，在该细胞类型中，它们不会在顶膜下方形成终末网，因此表明了刷状细胞类型的非外分泌功能。在牛皱胃的所有极化细胞中，肌动蛋白丝位于连接复合体的两个顶端成员，即紧密连接和黏着连接之下，在那里它们可能参与细胞黏附、细胞运动和细胞形状确定的调控。
