. The American journal of anatomy. tages, shows a distinct division into tw^o or three layers, with thenuclei situated approximately in the middle of the cell. The thickeningon the edge of the cell lining the lumen is apparent, although cilia are asyet unformed. As the branches of the tree are followed towards theperiphery, the layers of circularly directed syncytial cells disappear andwe have simply the primitive basement membrane with the connective-tissue cells immediately about it. In the most terminal parts of theair passages, the double layer of epithelium has been replaced by a singlela
. The American journal of anatomy. tages, shows a distinct division into tw^o or three layers, with thenuclei situated approximately in the middle of the cell. The thickeningon the edge of the cell lining the lumen is apparent, although cilia are asyet unformed. As the branches of the tree are followed towards theperiphery, the layers of circularly directed syncytial cells disappear andwe have simply the primitive basement membrane with the connective-tissue cells immediately about it. In the most terminal parts of theair passages, the double layer of epithelium has been replaced by a singlelayer of lower columnar epithelium (Fig. 23?>). All of the bronchi 9C The Development of the Lungs from the first to last possess marked lumina. From the root of the lung,the lymphatics have now grown some distance into its substance. Theyhave thin walls composed of young fibrils lined by endothelium withoccasional valves. They are confined, however, to the immediate neigh-borhood of the main bronchi and their chief
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectanatomy, bookyear1901
