Cossar D, Bell J, Lang M, Hume R
Department of Pathology, University of Edinburgh, Scotland.
In Vitro Cell Dev Biol Anim. 1993 Apr;29A(4):319-24. doi: 10.1007/BF02633960.
In utero, at around 23 wk gestation, the progenitor epithelium of distal airway differentiates into type I and type II pneumatocytes. Human fetal lung organ cultures, as early as 12 wk gestation, have the competence to self-differentiate. Distal airway epithelial immunoreactivity to cytokeratins CK 7, 8, and 18 decreases with differentiation both in utero and in organ culture, whereas reactivity to epithelial membrane antigen remains constant in both. As distal airways dilate, the mean percentage airspace of fetal lungs in organ culture increases to 58%, equivalent to lung of gestation 26.0 +/- 7.3 wk. In organ culture, capillary blood vessels, visualized by vimentin immunoreactivity, remodel and more closely approximate the epithelium but without direct invasion. In utero, at 23 wk gestation, elastin appears as condensation around airways and forms a basis for secondary crests which, by 29 wk gestation, evolve into alveolar septae. In organ culture, no elastin is deposited, no secondary or alveolar crests form, and the lung retains a simple saccular structure. Differentiation of the terminal airway epithelium and mesodermal maturational events to facilitate gas exchange, such as capillary invasion or secondary-alveolar crest formation, are almost synchronous in human lung in utero but clearly dissociate in organ culture.
在子宫内，妊娠约23周时，远端气道的祖上皮分化为I型和II型肺上皮细胞。早在妊娠12周的人胎儿肺器官培养物就具有自我分化的能力。在子宫内和器官培养中，远端气道上皮对细胞角蛋白CK 7、8和18的免疫反应性随分化而降低，而对上皮膜抗原的反应性在两者中均保持恒定。随着远端气道扩张，器官培养中胎儿肺的平均气腔百分比增加到58%，相当于妊娠26.0±7.3周的肺。在器官培养中，通过波形蛋白免疫反应性可视化的毛细血管进行重塑，并更接近上皮，但没有直接侵入。在子宫内，妊娠23周时，弹性蛋白出现在气道周围的凝结物中，并形成次级嵴的基础，到妊娠29周时，次级嵴演变成肺泡隔。在器官培养中，没有弹性蛋白沉积，没有形成次级或肺泡嵴，肺保持简单的囊状结构。终末气道上皮的分化和促进气体交换的中胚层成熟事件，如毛细血管侵入或次级肺泡嵴形成，在子宫内的人肺中几乎是同步的，但在器官培养中明显分离。
