Vijayan V, Tan C E
Department of Paediatric Surgery, Singapore General Hospital, Singapore.
Anat Rec. 1997 Nov;249(3):389-98. doi: 10.1002/(SICI)1097-0185(199711)249:3<389::AID-AR10>3.0.CO;2-K.
In the development of the human biliary system, although the extrahepatic bile ducts develop from the embryonic hepatic diverticulum, there is increasing evidence to suggest that the intrahepatic bile ducts originate within the liver from the ductal plate. The ductal plate develops as a sheath of primitive biliary epithelium in the mesenchyme along the portal vein branches. Through an orderly process of selection and deletion, the ductal plate is remodelled into the adult system of anastomosing tubular bile ducts. The ductal plate remodelling process occurs at the porta hepatis between 11 and 13 weeks of gestation and progresses towards the periphery of the liver.
In this project, for the first time, we have used computerised three-dimensional reconstruction techniques to visualise the developing human biliary system. Paraffin-embedded tissue from eight human embryos or fetuses between 5.5 and 16 weeks of gestation were serially sectioned, and their images were aligned, digitised, and used for three-dimensional reconstruction.
Three-dimensional images of the extrahepatic and the intrahepatic biliary systems were obtained, and the following conclusions were drawn. (1) The intrahepatic biliary system, both at the porta hepatis and within the liver, developed from the ductal plate through a consistent pattern of remodelling. (2) Prior to the remodelling process, the ductal plate was of similar morphology irrespective of site and gestation. (3) The extrahepatic biliary system was in direct luminal continuity with the developing intrahepatic biliary system throughout gestation and did not show the presence of a "solid stage" in any of the embryos or fetuses studied.
在人类胆道系统的发育过程中，尽管肝外胆管由胚胎肝憩室发育而来，但越来越多的证据表明肝内胆管起源于肝脏内的胆管板。胆管板在沿门静脉分支的间充质中作为原始胆管上皮的鞘而发育。通过有序的选择和删除过程，胆管板被重塑为成人的吻合管状胆管系统。胆管板重塑过程发生在妊娠11至13周时的肝门处，并向肝脏周边发展。
在本项目中，我们首次使用计算机三维重建技术来可视化发育中的人类胆道系统。对来自8个妊娠5.5至16周的人类胚胎或胎儿的石蜡包埋组织进行连续切片，并将其图像对齐、数字化并用于三维重建。
获得了肝外和肝内胆道系统的三维图像，并得出以下结论。（1）肝门处和肝脏内的肝内胆道系统均通过一致的重塑模式从胆管板发育而来。（2）在重塑过程之前，无论部位和妊娠情况如何，胆管板的形态相似。（3）在整个妊娠期，肝外胆道系统与发育中的肝内胆道系统在管腔上直接连续，在所研究的任何胚胎或胎儿中均未显示存在“实性阶段”。
