Functional and morphological analysis of the main excretory duct V Investigation of tuft cells by high pressure freezing and freeze substitution

大鼠颌下腺由形成初级唾液的分泌端和将初级唾液输送到口腔的导管系统组成。吻合导管的口径通常逐渐增加，在形态学和生理学上依次定义如下：管系上皮中除嵌套管、颗粒曲管、条纹管、排泄管、主排泄管和涎腺外，Tuft细胞普遍存在于胃肠道、呼吸道等各种中空器官的粘膜上皮中。提出了吸收、重吸收和分泌等功能。然而，它们的功能仍然很模糊。高压冷冻和冷冻替代的细胞可以很好地保存细胞内成分。据推测，通过该技术固定的组织仍处于活状态。1995-1997年的研究结果如下：7.1)我们建立了除插管外的导管系统的精细结构，这在形态学上显示了对初代唾液的修饰以产生终代唾液的贡献。2)我们发展了用镊子反复敲打唾液腺并在固定中摇动唾液腺的技术来阐明唾液腺腺泡。3)我们检查了主细胞、簇状细胞和暗细胞的分布，并对导管系统进行了形态计量学分析。在横纹管内分布的簇状细胞较少，而在管门处分布较多。暗室均匀地分布在整个管道系统中。4)采用高压冷冻和冷冻替代技术（HPE-FS）对雄性大鼠颌下腺主排泄管簇状细胞进行冷冻处理。我们比较了HPF-FS与常规化学固定（CF）获得的精细结构。

The rat submandibular gland consists of the secretory endpices that form the primary saliva, and the duct system that conducts the primary saliva to the orifice. The ducts anastomosead generally progressively increase in caliber, and were defined morphologically and physiologically in turn as follows ; the intercalated duct, the granular convoluted duct, the striated duct, the excretory duct, the main excretory duct and the salivary bladder, Tuft cells are commonly present in the epithelium of the duct system except the intercalated and the granular convoluted ducts, Tulf cells have a widespread occurrence in the mucous epithelium of the various hollow organs such as gastrointestinal and respiratory tracts. Such functions as reception, the reabsorption and secretion are proposed. However, their functions are still obscure. High pressure freezing and freeze substitution of tult cells result in excellent preservation of intracellular component. It is supposed that tissue fixed by the technique remains in aliving state. Following results were obtained during 1995-1997.1) We established the fine structure of duct system except of the intercalated duct, which showed morphologically the contribution for modifying the primary saliva to make a final saliva.2) we developed thetechnique to elucidate acini of salivary gland by repeat of tapping a salivary gland with tweezers and shaking it in the fixation.3) We examined the distribution of principal, tuft and dark cells and performed morphometric analysis of the duct system. Few tuft cells were distributed in the striated duct and most were doung at the hilus. Dark cells were equally distribution through out the duct system.4) High pressure freezing and freeze substitution technique (HPE-FS) were appplied to tuft cells of the main excretory duct of male rat submandibular gland. We compared the fine structure of the HPF-FS with that obtained using conventional chemical fixation (CF).