Oaks J A, Holy J M
Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin--Madison 53706-1102.
Exp Parasitol. 1994 Nov;79(3):292-300. doi: 10.1006/expr.1994.1092.
The free-surface of the tapeworm's tegument was examined for morphological evidence of secretion after fixation by rapid freezing-freeze substitution and alternatively by immersion in low concentrations of glutaraldehyde maintained at room temperature. After low-aldehyde fixation, omega profiles were at the bases of tegumental microvilli, arguing for the participation of some of the ectocytoplasm's vesicles in secretion of their contents to the intestinal lumen. The almost instantaneous fixation provided by the rapid freezing-freeze substitution technique documents the constitutive production of 0.03 to 0.075-micron microvesicles from outpocketings from the plasma membrane of the tegumental brush border. Observed in secretory epithelial cells of other species, microvesicles are recognized as a secretory pathway for constituent molecules of surface membranes. We conclude that in addition to the primary route of merocrine exocytotic secretion provided by the fusion of the Golgi-derived, ectocytoplasmic vesicles at the bases of the brush border microvilli, tegumental microvesicles provide a second secretory pathway for endogenous macromolecules across the tegumental free surface.
通过快速冷冻-冷冻置换固定，以及在室温下浸入低浓度戊二醛固定后，检查绦虫体表的自由表面，以寻找分泌的形态学证据。低醛固定后，ω形轮廓位于体表微绒毛的基部，这表明一些外质体囊泡参与了其内容物向肠腔的分泌。快速冷冻-冷冻置换技术提供的几乎瞬间的固定记录了从体表刷状缘质膜的袋状突出物中组成性产生0.03至0.075微米的微囊泡。在其他物种的分泌上皮细胞中观察到，微囊泡被认为是表面膜组成分子的分泌途径。我们得出结论，除了由高尔基体衍生的外质体囊泡在刷状缘微绒毛基部融合提供的局部分泌胞吐分泌的主要途径外，体表微囊泡还为内源性大分子提供了第二条穿过体表自由表面的分泌途径。
