THE LIVER 



177 



of cells, the hepatic duct (Fig. 185 ^4). That portion of the hepatic diverticulum 

 distal to the hepatic duct is now differentiated into the terminal, solid gall bladder 

 and its cystic duct. Its proximal portion forms the ductus choledochus. In embryos 

 of 10 mm. (Fig. 185 B) the gall bladder and ducts have become longer and more 

 slender. The hepatic duct receives a right and left branch from the corresponding 

 lobes of the Hver. The gall bladder is without a lumen up to the 15 mm. stage. 

 Later its cavity appears, surrounded by a wall of high columnar epithelium. 



The glandular portion of the Kver develops fast and is largest relative to the 

 size of the body at 31 mm. (Jackson). In certain regions the liver tissue under- 

 goes degeneration, and especially is this true in the peripheral portion of the left 



e 



B 



Fig. 186. — Diagrams of three successive stages of the portal and hepatic veins in a growing liver: 

 a. Hepatic side; d, portal side; 6 and c, successive stages of the hepatic vein; e and/, successive stages of 

 the portal vein (Mall). 



lobe. In general, the external lobes of the liver are moulded under the influence 

 of the fetal vitelline and umbiHcal trunks. 



The development of the hgaments of the hver is described on p. 192. 



During the development of the liver the endothelial cells of the sinusoids become stellate 

 in outline, and thus form an incomplete layer. From the second month of fetal life to some 

 time after birth, blood cells are actively developed between the hepatic cells and the endo- 

 thehum of the sinusoids. Lumina bounded by five or six cells may be observed in some of 

 the liver trabeculae of 10 mm. embryos (Lewis). At 22 mm. hollow periportal ducts develop, 

 spreading inward from the hepatic duct along the larger branches of the portal vein. In 

 44 mm. (C R) fetuses, bile capillaries with cuticular borders are present, most numerous near 

 the periportal ducts with which some of them connect. At birth, or shortly after, the number 

 of liver cells surrounding a bile capillary is reduced to two, three, or four. Secretion of the 

 bile commences at about the end of the third fetal month. 



