280 



HISTOLOGY 



liver approaches and fuses with the body wall immediately in front of the right subcar- 

 dinal vein. This fusion constitutes the coronary ligament (cf. Fig. 275); and across it, 

 the subcardinal vein anastomoses with the hepatic sinusoids. By a rapid enlargement 

 of this anastomosis, the trunk of the vena cava inferior is formed. It drains the 

 posterior cardinal system of veins, and the outlet of the vitelline veins into the heart be- 

 comes the terminal portion of the inferior vena cava; the main vessel from the liver, the 

 hepatic vein, is thereafter described as a branch of the vena cava inferior. The devel- 

 opment of the posterior part of the vena cava inferior is described in connection with 

 the Wolffian body (p. 309); for a fuller account, see the Amer. Journ. Anat., 1902, vol. 

 i, pp. 229-244. Occasionally the trunk of the vena cava is entirely surrounded by a 

 band of hepatic tissue, as in Fig. 275. 



rs-c.v. / aa l.s-c.v. 



r.t.l. 



i-l.o. 



f.l. v'um. 



FIG. 274. CROSS SECTION OF A MAMMALIAN 

 EMBRYO, TO SHOW THE ADHESION, *., BE- 

 TWEEN THE RIGHT LOBE OF THE LIVER AND 

 THE DORSAL ABDOMINAL WALL. 



ao., Aorta; f. c., fibrous capsule and serosa; f. 1., 

 falciform ligament; g. o., greater omentum; 

 1. o., lesser omentum; 1. s-c. v., left subcar- 

 dinal vein; o. b., omental bursa; r. s-c. v. f 

 right subcardinal vein; St., stomach; v. um., 

 left umbilical vein. 



1.0.- 



FIG, 275. DORSAL SURFACE OF THE ADULT 

 LIVER. 



c. 1., Coronary ligament; f. 1., falciform liga- 

 ment; g. b., gall bladder; 1. o.j lesser 

 omentum; 1. t. 1., left triangular ligament; 

 o. b., caudate lobe bounding the omental 

 bursa ventrally; p. v., portal vein; r. 1., 

 round ligament; r. t. 1., right triangular 

 ligament; v. c. i., vena cava inferior. 



Lobes of the liver. The structures already described form the bound- 

 aries of the lobes of the liver, which in man are few and not sharply marked 

 out. Right and left lobes have already been mentioned as the lateral 

 halves of the liver; they are not separated from one another by any internal 

 septum or indentation of the surface. The left lobe is relatively small, and 

 has a thin margin. It terminates in the appendix fibrosa at the extremity 

 of the left triangular ligament. This appendix represents a portion of the 

 liver from which the hepatic cells have degenerated and disappeared, leav- 

 ing chiefly the anastomosing ducts. It indicates that in earlier stages the 

 left lobe was more extensively developed. Similar tissue containing 

 aberrant ducts (vasa aberrantia] may be found around the vena cava and 

 in some other parts of the liver. The quadrate lobe is marked out by the 

 porta, the round ligament, and the fossa containing the gall bladder. The 

 caudate lobe is bounded by coronary ligament, lesser omentum and porta. 

 The caudate process of this lobe extends to the right lobe over the foramen 

 epiploicum (of Winslow) between the vena cava and the porta. 



The hepatic artery. The liver in an embryo of 10 mm. has no arteries, 

 but at that stage the hepatic artery can be followed to the porta. Later it 



