The development of the human body; a manual of human embryology . nosus; L, liver; pm, ventralpancreas; rL, right lobe of the liver; S, stomach.—(Hammar.) sent the right (rL) and left lobes of the adult liver. Theremaining definitive lobes, the spigelian, quadrate andcaudate, are of later formation, the first two standing inrelation to the vessels which cross the lower surface of theliver, while the caudate is formed by a portion of the rightlobe which arches across the upper part of the ductusvenosus. The ductus communis choledochus is at first wide and THE LIVER. 327 short, and near its prox
The development of the human body; a manual of human embryology . nosus; L, liver; pm, ventralpancreas; rL, right lobe of the liver; S, stomach.—(Hammar.) sent the right (rL) and left lobes of the adult liver. Theremaining definitive lobes, the spigelian, quadrate andcaudate, are of later formation, the first two standing inrelation to the vessels which cross the lower surface of theliver, while the caudate is formed by a portion of the rightlobe which arches across the upper part of the ductusvenosus. The ductus communis choledochus is at first wide and THE LIVER. 327 short, and near its proximal end gives rise to a small out-growth on each side, one of which becomes the ventralpancreas (Fig. 178, B, pm). Later it elongates and be-comes more slender, and the gall-bladder is constricted offfrom it, the connecting stalk becoming the cystic hepatic ducts are apparently developed from theliver substance and are relatively late in appearing. Shortly after the hepatic portion has been differen-tiated its substance becomes permeated by numerous. Fig. 175.—Transverse Section through the Liver of an Embryo ok Four Months. in, Intestine; /, liver; W, Wolffian body.—(Toldt and Zuckerkandl.) blood-vessels, and so divided into numerous anastomosingtrabecular (Fig. 175). These are at first irregular in sizeand shape, but later they become more slender and moreregularly cylindrical, forming what have been termed thehepatic cylinders. In the center of each cylinder, wherethe cells which form it meet together, a fine canal appears,the beginning of a bile capillary, the cylinders thus be-coming converted into tubes with fine lumina. This oc- 328 THE DEVELOPMENT OF THE HUMAN BODY. curs at about the fourth week of development and at thistime a cross-section of a cylinder shows it to be composedof about three or four hepatic cells (Fig. 176, A), amongwhich are to be seen groups of smaller cells (e) which areerythrocytes, the liver having assumed by this time itshaematopo
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectembryol, bookyear1902
