Adamson C L, Davis R L
Rutgers University, Department of Cell Biology and Neuroscience, Piscataway, NJ 08854-8082, USA.
Hear Res. 1999 Mar;129(1-2):111-27. doi: 10.1016/s0378-5955(98)00225-1.
The marginal cells of the stria vascularis possess distinctive morphological characteristics associated with their role in endolymph production. Interestingly, when stria-derived epithelial cells are grown in association with the underlying mesenchyme, the final differentiation of these cell types does not occur. Beyond the rudimentary polarity that is established, similar to that shown in epithelial monolayers, cells in culture bear only a slight resemblance to their marginal cell counterparts in vivo. The ultrastructural features that typify these epithelia, extensive cytoplasmic invaginations, with an abundance of mitochondria, and darkly stained cytoplasm, are not evident under standard culture conditions. In order to determine whether fluid transport, a key function of the stria vascularis, has an effect on the ultrastructural morphology, we examined de novo stria vascularis tissues that formed a fluid-filled cyst in vitro. We found that only cells associated with the luminal structure demonstrated dark cytoplasmic staining and amplification of the basolateral membrane of the marginal cells. Additionally, other epithelial features, such as mitochondria-rich and microvilli-rich cells, were observed in cyst-forming tissues. The enhancement of the marginal cell specializations was not as robust as that observed in vivo; however, they were clearly more extensive when compared to cells in the same culture that were not associated with a fluid-filled lumen. Thus it appears that fluid transport may be necessary to maximize differentiation of stria vascularis tissues in vitro.
血管纹的边缘细胞具有与其在内淋巴生成中的作用相关的独特形态特征。有趣的是，当源自血管纹的上皮细胞与下方的间充质一起生长时，这些细胞类型的最终分化不会发生。除了建立的基本极性外，类似于上皮单层中显示的极性，培养中的细胞与体内的边缘细胞对应物只有轻微的相似之处。在标准培养条件下，这些上皮细胞典型的超微结构特征，即广泛的细胞质内陷、丰富的线粒体和深色染色的细胞质并不明显。为了确定血管纹的关键功能——液体运输是否对超微结构形态有影响，我们检查了在体外形成充满液体囊肿的新生血管纹组织。我们发现，只有与管腔结构相关的细胞表现出深色细胞质染色和边缘细胞基底外侧膜的扩增。此外，在形成囊肿的组织中还观察到其他上皮特征，如富含线粒体和富含微绒毛的细胞。边缘细胞特化的增强不如在体内观察到的那样强烈；然而，与同一培养物中不与充满液体的管腔相关的细胞相比，它们明显更广泛。因此，似乎液体运输可能是使血管纹组织在体外最大限度分化所必需的。
