ABSTRACT
This study included twenty human foetuses during various periods of gestation ranging from 9 to 40 weeks. The age of the foetus was approximately determined. Specimens from the liver were obtained and subjected to the appropriate histological and histochemical techniques. The data revealed that the bile duct system was immature at 9 weeks-old foetuses. Then at the 11th week, groups of hepatic cells were arranged in close contact with portal vein branches. At 12 weeks-old foetuses, the biliary ducts started to appear as small spaces among these groups of hepatic cells. At 18 to 20 weeks, portal spaces became obvious and duct-like structures were observed in the parenchyma-connective tissue contact area around these portal spaces. From the 21st week onwards, developing biliary structures were observed at the margins of the portal spaces. Then the portal mesenchymal tissue successively surrounded the bile ducts and pushed them inside portal spaces. At week 40, the number of large individual bile ducts increased in each portal area. The present results suggested that the cells lining the developing biliary structures originated from the hepatoblasts. The number of ductular structures per portal tract increased in full term foetal liver. Nevertheless, the bile canalicular system was less conspicuous till the full term gestational period suggesting that development will continue in the postantal life