MECHANISMS OF SALIVARY GLAND DEVELOPMENT

啮齿动物的下颌下腺（SMG）是研究下颌下腺功能的一个很好的系统。 分泌上皮的发育，因为几种分泌细胞类型 出现沿着共同管和腺体不达到成熟，直到3至 4个月大。 此外，改变比例的可能性 这些导管分泌细胞在整个成年期保留。 通过 利用特定的细胞类型标记， 可以通过发展来收回。 腺泡细胞（AC）未出现 直到出生后3天，但粘蛋白，AC免疫定量研究 标记，表明粘蛋白存在于产前动物，之前， AC的出现。 粘蛋白的积聚模式是双相的 性质，表明AC通过前原分化阶段 细胞分化。 敏感的蛋白质合成分析将是 以验证粘蛋白合成发生在这个阶段。 表皮生长因子的免疫定量和蛋白合成研究 (EGF)将决定颗粒曲小管细胞（GCT）是否同样 经过原分化阶段。 产前和成人的克隆 将进行SMG，以确定GCT和AC是否共用一个股骨柄 在发育过程中的细胞和成人的细胞替代。 链路 分化和细胞替代之间的关系将进一步研究， 通过细胞分选分离纯GCT和纯Ac群体， 看看每种分化的细胞类型是否保留了原始分化的 另一种能力。 最近的研究表明，粘蛋白存在于颗粒 闰管细胞（GID）来自成年女性腺体。 也许这些细胞 是AC替换过程中的中间体。 利用成果 从分泌单位的三维重建和DNA标记， 应提供是否有横纹分泌 肾小管细胞（SST）和GID分别是GCT和AC的中间体， 在更换过程中。 这些观察也可能提供证据 对于成年人的多能干细胞，或者相反，对于个体， 每种分泌细胞类型的祖细胞系。 最终，我们要确定分泌细胞 下颌下腺的发育顺序不同， 以确定基因控制的水平。

The rodent submandibular gland (SMG) poses an excellent system to study the development of secretory epithelium because several secretory cell types arise along a common duct and the gland does not reach maturity until 3 to 4 months of age. Furthermore, the potential for changing the proportions of these ductal secretory cells is retained throughout adulthood. By utilizing specific cell type marker, differentiation of various cell types can be racked back through development. Acinar cells (AC) do not appear until 3 days after birth, yet immunoquantitation studies of mucin, an AC marker, indicate that mucin is present in prenatal animals, prior to the appearance of AC. The pattern of accumulation for mucin is a biphasic nature, indication that AC pass through a protodifferentiated stage prior to cytodifferentiation. Sensitive protein synthesis assays will be performed to verify that mucin synthesis occurs during this stage. Immunoquantitation and protein synthesis studies on epidermal growth factor (EGF) will determine if granular convoluted tubule cells (GCT) likewise pass thought a protodifferentiated stage. Cloning of prenatal and adult SMG will be performed determine whether GCT and AC share a common stem cell during development and for cell replacement in adults. The link between differentiation and cell replacement will be pursued further by isolating pure GCT and pure Ac populations by cell sorting and then testing to see if each differentiated cell type retains the protodifferentiated capability for the other. Recent studies have shown that mucin is present in the granular intercalated duct cell (GID) from adult female glands. Perhaps these cells are an intermediate in the AC replacement process. By utilizing results from 3-D reconstructions and DNA labelling of secretory units, an indication should be provided as to whether or not striated secretory tubule cells (SST) and GID are intermediates of GCT and AC, respectively, in the replacement process. These observations may also provide evidence for a pleuripotent stem cell in adults or conversely, for individual progenitor cell lines for each secretory cell type. Ultimately, we are tying to determine at what stage secretory cell divergence occurs in the sequence of development of submandibular gland and to identify the level of gene control that is responsible.