Herbst R, Multier-Lajous A M, Grabitz K, Hoder D, Kober H J, Blümcke S
Z Mikrosk Anat Forsch. 1979;93(4):736-50.
The development of the bronchial and alveolar epithelium was observed in rabbits from the 15th day post conception until the time of birth with the scanning electron microscope. In the pseudoglandular phase, primitive bronchi proliferate in the mesenchyme. The epithelial cells are not differentiated and have single cilia. After retraction of these single cilia cell differentiation begins. Flat cells densely populated with cytopodia can be recognized on the 22nd day, ciliated cells on the 23rd day post conception. Both are located in the bronchi near the hilus. In the canalicular phase of development, the differentiation of the mucoid cells and the Clara-cells begins. The interstitial connective tissue develops more and more capillaries. The alveolar phase begins around the 26th day p. c. The lung capillaries reach the alveolar epithelial cells and arrange themselves directly beneath the epithelial basement membrane. This "alveolarization" of the lung tissue starts in the centre of the lung lobules and proceeds to the periphery. After the 26th day post conception the alveolar epithelial cells retract their single cilium and at the same time become type I or type II pneumocytes. The undifferentiated entodermal stem cell of the alveolar epithelium is the pneumoblast.
从受孕后第15天直至出生，用扫描电子显微镜观察了家兔支气管和肺泡上皮的发育情况。在假腺期，原始支气管在间充质中增殖。上皮细胞未分化，有单个纤毛。这些单个纤毛缩回后，细胞分化开始。在受孕后第22天可识别出充满细胞足的扁平细胞，第23天可识别出纤毛细胞。两者都位于肺门附近的支气管中。在发育的小管期，黏液细胞和克拉拉细胞开始分化。间质结缔组织形成越来越多的毛细血管。肺泡期大约在受孕后第26天开始。肺毛细血管到达肺泡上皮细胞，并直接排列在上皮基底膜下方。肺组织的这种“肺泡化”始于肺小叶中心，并向周边发展。受孕后第26天之后，肺泡上皮细胞缩回其单个纤毛，同时变成I型或II型肺细胞。肺泡上皮未分化的内胚层干细胞是成肺细胞。
