Pearsall A D
Department of Anatomy, Baylor College of Dentistry, Dallas, Texas 75246.
Am J Anat. 1989 Oct;186(2):173-85. doi: 10.1002/aja.1001860207.
Throughout the epithelial lining of the respiratory system is a class of cells with characteristics similar to Amine Precursor Uptake and Decarboxylation (APUD) polypeptide hormone-producing cells. In the intrapulmonary airways, these small-granule cells (SGCs) occur either singly or in organized clusters. Although no specific peptide has yet been identified, subclasses have been postulated based on granule geometry or light microscopic staining. The present study characterizes the architectonic and cellular organization of clustered SGCs in the adult Syrian golden hamster. Two morphologically distinct cells can be defined in such clusters, "light" and "dark." Thid distinction was based primarily on differences in the electron density of the cytoplasmic matrix rather than on the remarkable variations in cellular organelles or dense-core secretory vesicles. Both cell types were normal as judged by uniform spherical nuclei, chromatin organization, and distribution of cellular organelles. The "dark" cells, however, presented the profile of a cell actively involved in synthesis with a markedly dilated perinuclear cisterna and endoplasmic reticulum. Additionally, the "dark" cells contained membrane-delimited structures containing concentric membranous whorls, clear vacuoles, and lipofuscin granules. Occasionally, cells were observed to contain features of both cell types, suggesting that they may represent a continuum of common cell lineage. Accordingly, in the absence of additional morphologic or biochemical data, the "light" and "dark" cells most probably correspond to different stages of functional activity or age-related changes of a single type of cell. Unmyelinated nerve endings were occasionally interposed between cells, but synaptic specializations were not observed. Beneath the clusters, nerve fibers were also present, but they were never observed to penetrate the basal lamina or contact any of the SGCs. Of equal occurrence were elements of the vascular system and smooth muscle, suggesting that some SGCs in the adult hamster may function in a paracrine or endocrine manner. Such knowledge is essential to any study attempting to delineate the functional role or roles of these enigmatic organoids.
在整个呼吸系统的上皮衬里中，存在一类细胞，其特征与胺前体摄取和脱羧（APUD）多肽激素产生细胞相似。在肺内气道中，这些小颗粒细胞（SGCs）单独出现或成有组织的簇状出现。尽管尚未鉴定出特定的肽，但已根据颗粒形态或光学显微镜染色推测出亚类。本研究描述了成年叙利亚金黄地鼠中簇状SGCs的结构和细胞组织。在这样的簇中可以定义两种形态上不同的细胞，即“亮”细胞和“暗”细胞。这种区分主要基于细胞质基质电子密度的差异，而不是细胞器或致密核心分泌小泡的显著变化。从均匀的球形细胞核、染色质组织和细胞器分布来看，两种细胞类型都是正常的。然而，“暗”细胞呈现出一个积极参与合成的细胞的特征，其核周池和内质网明显扩张。此外，“暗”细胞含有膜界定的结构，其中包含同心膜性涡旋、透明空泡和脂褐素颗粒。偶尔会观察到细胞同时具有两种细胞类型的特征，这表明它们可能代表了一个共同细胞谱系的连续体。因此，在没有额外的形态学或生化数据的情况下，“亮”细胞和“暗”细胞很可能对应于单一类型细胞的功能活动或与年龄相关变化的不同阶段。无髓神经末梢偶尔插在细胞之间，但未观察到突触特化。在簇的下方也存在神经纤维，但从未观察到它们穿透基膜或接触任何SGCs。血管系统和平滑肌的成分同样存在，这表明成年仓鼠中的一些SGCs可能以旁分泌或内分泌方式发挥作用。这些知识对于任何试图描绘这些神秘类器官功能作用的研究来说都是至关重要的。
