These epithelial elements arise embryologically from foregut endoderm in the process of bronchial tubular growth . 这些表皮细胞在胚胎学上把源于支气管生长过程中的前内脏叫内胚层。
2.
Since left colic flexure is a segment of embryonic hindgut and the splenic artery typically supplies the foregut , the condition in which an artery of foregut crosses midgut to supply an area of the hindgut becomes interesting 本例中变异之动脉发源自供应前肠之脾动脉，再跨越了胚胎中肠部份，而供应原属于后肠发育出之结肠左曲，实为一种罕见的变异状况。
