Development of the sphincteric apparatus of the extrahepatic bile ducts in the prenatal period of human ontogenesis

Abstract

In this study, authors found the sources of anlages, and the peculiarities in development and formation of topography of structural components of sphincteric apparatus of the extrahepatic bile ducts (EBD). We found that beginning from the sixth month of the development, EBD are traced in the form of a well-defined tubular structure. The extrahepatic and intrahepatic bile ducts are well contoured, but in the end of the embryonal period, a tendency to mutual fuse has been noticed. Formation of the intraorgan blood vessels of the common bile duct is detected at the end of the seventh week of the intrauterine development in fetuses starting with 18.0-19.0 mm of parietococcygeal length (PCL). The peculiarities of spatial structure of the arterial anastomoses around the coiled part of the cystic duct proved the existence of the locking device (sphincter) between the neck of gallbladder and cystic duct and play an important role in functioning of vascular (arterial) component of it. The peculiarities of topography and spatial structure differences in arterial and venous plexuses in the sphincter segments of the biliary system were observed clearly in the end of the fetus period of development and in newborns. This may indicate an important role of these vessels in the function of sphincters, which provides biliodynamics.