Hoyt R F, McNelly N A, Sorokin S P
Department of Anatomy, Boston University School of Medicine, Massachusetts 02118.
Anat Rec. 1990 Jul;227(3):340-50. doi: 10.1002/ar.1092270309.
Autoradiographs were prepared from lungs of a newborn Syrian golden hamster exposed continuously to 3H-thymidine for the final 4.5 days of a normal 16 day gestation. Silver grains were counted over nuclei of 1,298 small-granule endocrine cells in 165 neuroepithelial bodies (NEBs) in the right upper lobe and along the left axial bronchus, where nodal NEBs occurred at branch points and internodal NEBs in the airway between them. Nuclei of 1,005 nonendocrine airway epithelial cells were counted next to the NEBs. Label was distributed differently in the two populations: All nonendocrine cells were labeled, whereas many endocrine cells were not. In NEBs of the right upper lobe, total label (net grains/nuclear profile) averaged only 23% of that in nonendocrine cells. Along the left axial bronchus, mean label in nonendocrine cells and internodal NEBs rose 10-fold between the hilum and the periphery. Increases for both populations were linear and parallel, but total label in the NEBs was consistently lower than that in the surrounding epithelium by 15 grains/nuclear profile. Nodal NEBs were more lightly labeled than those of the internodes, consistent with their earlier formation. A few very heavily labeled small-granule cells (0.9%) occurred singly in the periphery of large, otherwise lightly labeled NEBs. Statistically these belonged to the labeling distribution of nearby nonendocrine cells. In contrast to NEBs, neurons in 10 bronchial ganglia of the right lung were virtually unlabeled. These arise from vagal neural crest and seem to comprise an entirely distinct population. We conclude that NEBs belong intrinsically to pulmonary endoderm, not neural crest. During fetal life each develops from a cell or cells programmed to stop dividing well ahead of other elements in the epithelium. Their formation is linked closely to early proliferation of the bronchial tree and is an integral part of growth and differentiation of the airway lining. After a wave of initial formation has passed down the airway, small-granule cells are added slowly to mature NEBs, probably through differentiation from adjoining airway epithelial cells--a potential mechanism for cell replacement in adult life.
对一只新生叙利亚金黄地鼠的肺组织制备了放射自显影片，该幼鼠在正常16天妊娠期的最后4.5天持续暴露于³H-胸腺嘧啶。对右上叶和左主支气管沿线165个神经上皮小体（NEBs）中的1298个小颗粒内分泌细胞的细胞核进行银颗粒计数，在分支点处有结节状NEBs，在它们之间的气道中有节间NEBs。在NEBs旁边对1005个非内分泌气道上皮细胞的细胞核进行计数。标记物在这两种细胞群体中的分布不同：所有非内分泌细胞都有标记，而许多内分泌细胞没有标记。在右上叶的NEBs中，总标记量（净颗粒数/核轮廓）平均仅为非内分泌细胞的23%。沿着左主支气管，非内分泌细胞和节间NEBs中的平均标记量在肺门和周边之间增加了10倍。两种细胞群体的增加都是线性且平行的，但NEBs中的总标记量始终比周围上皮细胞低15个颗粒/核轮廓。结节状NEBs的标记比节间的更浅，这与其较早形成一致。少数标记非常强烈的小颗粒细胞（0.9%）单独出现在大的、其他部分标记较浅的NEBs周边。从统计学上看，这些属于附近非内分泌细胞的标记分布。与NEBs不同，右肺10个支气管神经节中的神经元几乎没有标记。这些神经元起源于迷走神经嵴，似乎构成了一个完全不同的群体。我们得出结论，NEBs本质上属于肺内胚层，而非神经嵴。在胎儿期，每个NEBs都由一个或多个在上皮中比其他细胞成分更早停止分裂的细胞发育而来。它们的形成与支气管树的早期增殖密切相关，是气道内衬生长和分化的一个组成部分。在一波初始形成浪潮沿着气道传过后，小颗粒细胞可能通过从相邻气道上皮细胞分化而缓慢添加到成熟的NEBs中，这是成年期细胞替代的一种潜在机制。
