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Abstract Summery and conclusion The present study was carried out on 50 chick embryo of Dandarawi chicken collected from Assiut university farm at a 3, 5, 7, 9, 11, 13, 15, 17 and 19 day of prehatching life. At 3 day, the hepatic diverticulum gives dorsal and ventral parts in relation to the ductus venosus. At 7th day, the dorsal and ventral parts become the left and right lobes respectively where the gall bladder located on visceral surface of the right lobe and a transverse fissure dividing the left lobe into dorsal and ventral parts. At 9th day, the right lobe is longer and higher than the left one where the right lobe is contact dorsally with the mesonephros and the left one is separated from the mesonephros by the glandular stomach. At 11th day, the caudal vena cava crossing the lateral part of the right lobe. The interlobar fissure is occupied mainly by the umbilical vein. At 13th day, the parietal surface of the two lobes is related to the heart and body wall but visceral surface of the left lobe is related to muscular stomach and that of the right lobe is related medially to muscular stomach and laterally to the intestine and gall bladder. At 15th day, the cranial end of the right lobe has three processes dorsal, middle and ventral but the cranial end of the left lobe has two processes dorsal and ventral. Middle process appears at 11th day, and the middle process of the right lobe more prominent and caudal to that of the left one, but their relation differ as the middle process of the right lobe is located between the gallbladder and portal vein dorsally and the umbilical vein ventrally. The middle process of the left lobe is located ventral to the portal vein only. At 13th day, right middle process is divided caudally. At third day, the vitelline veins extend from the yolk sac to the heart on either side of the hepatic diverticulum. Near the heart, the two vitelline veins united together forming the ductus venosus which is continued cranially with the sinus venosus and its caudal part is the caudal vena cava. At 7th day, the vitelline veins caudal to the liver anastomose together forming the portal vein which gives off left portal branch to the left lobe of liver and continue as right portal branch to the right lobe. The gall bladder was observed in 5th day. In 7th day, it appears on visceral surface of the right lobe. In 11th day, the gall bladder appears dorsal to middle process of right lobe. In 13th day, it increases in size and extends laterally there fore its neck and body are located dorsal to middle process but fundus is lateral to it. The duct system of the right lobe is hepatocystic and cystoenteric, but that of the left is hepatoenteric duct. At 7th day, the left and right dorsal hepatic cavities could be observed but the ventral ones remain connecting with the plural cavity. The dorsal hepatic cavity related dorsally to the lung but at 9th days due to the appearance of the cranial thoracic air sacs the dorsal hepatic cavities separating from the lung by these sacs. At 9th day the ventral hepatic cavities are separated from the pleural cavities. At 9th day, as the dorsal hepatic cavities are located craniodorsal to that of the ventral hepatic cavities there for at the cranial end of the liver, the dorsal hepatic cavities are only observed, at the level of the esophagus appear dorsal and ventral cavities and at the level of the glandular stomach the ventral only observed. At 13th day, the left dorsal hepatic cavity connected with the intestinal coelomatic cavity but the right one is separated from the intestinal cavity by a septum. The dark cells increases in number on expanse to light cells. At 7th day the light cells become numerous and then after the gradually decrease to reach their minimum at 13th day, but at 15th day of incubation these cells are difficult to be observed. The width of the lumen of the sinusoid is reversely related to the age of the embryo. At 5th to 7th days of incubation, the mesothelium covering the liver is flat to cuboidal and at 9th day becomes flattened. Nucleus at 7th day is large, lightly stained and with two nucleolus gradually become dark and small. The hepatocytes increase in size gradually from 7th day to 19th day of incubation. In apical border of hepatocyte, there are microvilli which have maximum length at 7th day of incubation then decrease gradually until 19th day of incubation. Also the bile canliculi is wide at 7th day of incubation, it becomes narrow and reaching the narrowest level at 19th day of incubation. The lipid increases gradually from 7th day to gain its maximum at the 19th day. The mucopolysaccharide begins to increase gradually to gain its maximum at 9th day then after it reaches the lowest level at 11th day then increases in 13th day and continues at this level till end of incubation. |