Plopper C G, Halsebo J E, Berger W J, Sonstegard K S, Nettesheim P
Exp Lung Res. 1983 Sep;5(2):79-98. doi: 10.3109/01902148309061506.
Three types of nonciliated secretory epithelial cells are thought to contribute to the mucous lining of intrapulmonary airways: mucous cells, serous cells, and Clara cells. The Clara cell is distinguished from the other two by low cuboidal shape, presence of membrane-bound electron-dense ovoid secretory granuLes, abundant apical agranular endoplasmic reticulum (AER), and its location as the lining cell of distal conducting airways (bronchioles). The present study was designed to define the distribution of the Clara cell within the trachea and intrapulmonary airway tree. We correlated airway size, generation of branching, and airway wall components with Clara cell morphology and abundance. Lungs of 6 male rabbits (8-15 weeks old) free of respiratory disease were fixed by airway infusion of glutaraldehyde/paraformaldehyde at 30 cm pressure. The trachea, primary bronchi, and airways of the right cranial lobe of each lung were exposed by microdissection. The branching pattern was recorded and numbered. One half of the dissected lung was processed for scanning electron microscopy and the other half embedded as large epoxy blocks for simultaneous transmission electron and light microscopy. The percentages of ciliated, mucous, nonciliated, and basal epithelial cells were quantitated by light microscopy. Basal cells and peribronchial cartilage were absent distal to the fourth intrapulmonary generation in both the axial airway and its first major branch. Mucous (goblet) cells were present (less than 2%) only in trachea and primary and lobar bronchi. Nonciliated cells were more abundant distally, constituting 21%-45% of the epithelium in cartilaginous airways and 35%-65% in noncartilaginous ones. In the first six airway generations including trachea, nonciliated cells were without large apical protrusions but were covered by long microvilli. Cells of more distal airways had prominent apical protrusions and lacked microvilli. Nonciliated cells in all airways had abundant apical AER, granular endoplasmic reticulum (GER), and electron-dense ovoid granules. Cells in proximal airways were columnar rather than low cuboidal and had more GER. Only nonciliated cell shape, luminal surface, and granule abundance varied with airway size and generation. We concluded that the nonciliated secretory cell lining all intrapulmonary airways in the rabbit lung is one cell type, the Clara cell.
黏液细胞、浆液细胞和克拉拉细胞。克拉拉细胞与其他两种细胞的区别在于其低立方体形、存在膜结合的电子致密卵圆形分泌颗粒、丰富的顶端无颗粒内质网（AER），以及其作为远端传导气道（细支气管）内衬细胞的位置。本研究旨在确定克拉拉细胞在气管和肺内气道树中的分布。我们将气道大小、分支级数和气道壁成分与克拉拉细胞的形态和丰度进行了关联。对6只无呼吸道疾病的雄性兔子（8 - 15周龄）的肺，通过在30厘米压力下经气道注入戊二醛/多聚甲醛进行固定。通过显微解剖暴露每只肺的气管、主支气管和右颅叶气道。记录分支模式并编号。将解剖后的肺的一半用于扫描电子显微镜检查，另一半包埋成大的环氧树脂块用于同时进行透射电子显微镜和光学显微镜检查。通过光学显微镜对纤毛、黏液、无纤毛和基底上皮细胞的百分比进行定量。在轴向气道及其第一个主要分支中，第四级肺内分支远端不存在基底细胞和支气管周围软骨。黏液（杯状）细胞仅存在于气管、主支气管和叶支气管中（少于2%）。无纤毛细胞在远端更为丰富，在软骨性气道中占上皮细胞的21% - 45%，在非软骨性气道中占35% - 65%。在前六级气道（包括气管）中，无纤毛细胞没有大的顶端突起，但被长微绒毛覆盖。更远端气道的细胞有突出的顶端突起且没有微绒毛。所有气道中的无纤毛细胞都有丰富的顶端AER、颗粒内质网（GER）和电子致密卵圆形颗粒。近端气道中的细胞是柱状而非低立方体形，且有更多的GER。只有无纤毛细胞的形状、腔面和颗粒丰度随气道大小和级数而变化。我们得出结论，兔肺中衬于所有肺内气道的无纤毛分泌细胞是一种细胞类型，即克拉拉细胞。
