Brush cells have recently been classified as solitary chemosensory cells. However, tracheal brush cells have not been morphologically and immunohistochemically characterized yet. In the present study, the morphological and immunohistochemical characteristics of tracheal brush cells were analyzed using immunohistochemistry and scanning, and transmission electron microscopies. Brush cells in the tracheal epithelium were barrel-like or columnar in shape and were immunoreactive for villin. Scanning and transmission electron microscopies revealed densely arranged thick microvilli on the apical surface of tracheal brush cells and tubular membranous elements and/or vesicular formations in the supranuclear region. A morphometrical analysis of tracheal whole-mount preparations showed that the density of brush cells was greater in the cranial third and the mucosa on the annular ligament. Double immunofluorescence revealed that the morphology of villin-immunoreactive brush cells was distinct from other non-ciliated cells in the tracheal epithelium, i.e., MUC5AC-immunoreactive mucous cells, SNAP25-immunoreactive neuroendocrine cells, and GNAT3-immunoreactive solitary chemosensory cells. On the other hand, tracheal brush cells were immunoreactive for the marker proteins for intestinal brush cells, CK18, DCLK1, and Cox1; however, these antibodies also recognized cells other than brush cells. Furthermore, immunoreactivity for PKD2L1, a cation channel subunit, was detected in brush cells. The present results demonstrated that tracheal brush cells are independent cell types. These brush cells may be activated by acid and the secretion of prostaglandins. In conclusion, the present study revealed that tracheal brush cells are independent cell types based on the morphological and immunohistochemical characteristics.

刷细胞最近被分类为孤立的化学感觉细胞。然而，气管刷细胞尚未在形态和免疫组织化学上表征。在本研究中，使用免疫组织化学和扫描，以及透射电子显微镜对气管刷细胞的形态和免疫组织化学特征进行了分析。气管上皮中的刷状细胞呈桶状或柱状，对villin具有免疫反应性。扫描和透射电子显微镜检查显示，在气管刷细胞的顶表面和核上区域的管状膜元件和/或囊泡形成密集排列的厚绒毛。气管整装制剂的形态计量学分析表明，在颅第三韧带和环状韧带的粘膜中，刷状细胞的密度更高。双重免疫荧光显示，villin免疫反应性刷状细胞的形态不同于气管上皮中的其他非纤毛细胞，即MUC5AC免疫反应性粘液细胞，SNAP25免疫反应性神经内分泌细胞和GNAT3免疫反应性单性化学感觉细胞。另一方面，气管刷细胞对肠刷细胞CK18，DCLK1和Cox1的标记蛋白具有免疫反应性。然而，这些抗体也识别刷细胞以外的细胞。此外，在刷细胞中检测到对阳离子通道亚基PKD2L1的免疫反应性。目前的结果表明气管刷细胞是独立的细胞类型。这些刷毛细胞可以被酸和前列腺素的分泌激活。总之，本研究表明，基于形态学和免疫组化特征，气管刷细胞是独立的细胞类型。