CHANGES IN FETAL VESSELS OF THE LIVER 498 



Since the observations here reported were observed lai'geiy 

 incidentally no comprehensive detailed microscopic study of 

 the minute changes which accompany the processes of retraction, 

 atrophy and degeneration of the umbilical vein and hypogastric 

 arteries were made. However, quite a number of specimens 

 from several species were examined and from these it is evi- 

 dent that the microscopical picture of the so-called obliteration 

 of the umbilical vessels in the domestic animals, save rarely, is 

 not practically concluded a few weeks after birth as Kirchbach 

 asserts is true of the ductus venosus and vena umbilicalis in man . 

 Kirchbach's statement in contradicted also by Haberda. At- 

 tention has already been called to the fact that, as a rule, the 

 umliilical vein in both the dog and sheep disappears totally in 

 the course of a few months. From examination of the remnants 

 of the \'eins found before this time and from other facts stated 

 above it is obvious that in the animals examined, this oblitera- 

 tion, atrophy, degeneration and absorption is invariably centrip- 

 etal and not contrifugal as Robin says is the case in man. The 

 free distal extremities of the filaments representing the rem- 

 nants of the umbilical vein which were still attached to the left 

 portal, were composed of vascular ill-preserved, fibrous con- 

 nective tissue enclosed in peritoneum except in case of one 

 lamb in which bundles of muscle fibers were preserved even in 

 the degenerating tip. Farther proximally, i.e. nearer the left 

 portal, a small remnant of the umbilical vein remained, but 

 still farther centrally a remnant of the lumen was also present, 

 and finally a portion of the original vessel with well-preserved 

 walls somewhat reduced in size could be recognized. In case 

 of the lamb about 5 to 7 weeks old the small degenerating remnant 

 of the vein which was approximately 2 cm. long containetl a 

 macroscopic lumen for about half its extent but the intima 

 was poorly preserved and absent in places. There was no 

 proliferation of the endothelium and an elastica interna was not 

 noticed in Van Gieson stains. The media which had undergone 

 a hyaline degeneration, was represented only bj^ a granular 

 detritus in some places and small degenerating nuclei wei-e 

 accunmlated in it near the lumen. There was no distinc^t 



