STUDIES OF THE HUMAN FETAL LIVER A LIGHT, ELECTRON MICROSCOPIC AND FREEZE-FRACTURE REPLICA STUDY / 解剖学报

ABSTRACT

The livers from 5 week 14～32 human fetuses were studied. The results are summarized as follows1. Two kinds of liver cells revealed by EM the "light" and "dark" cells. The light ones are larger in size, more numerous in number, containing larger mitochondria and obvious RER and SER, but less free ribosomes than the dark ones. Both of them may contain hemosiderin granules and the configuration of mitochondria enclosed by circular or semicircular RER cisternae.2. Bile canaliculus Beside canaliculi between two adjacent liver cells, canaliculi situated between 3 or 4 liver cells are not infrequently revealed. That is due to the fetal liver cells are arranged in groups rather than in cords. The stereoscopic configurations of bile canaliculus and the tight junction surrounding it are demonstrated more clearly in freeze-fracture micrograph than that of the TEM. In addition, one intracellular bile canaliculus is found in the freeze-fracture preperation.3. The blood sinusoid and hemopoietic focus In the 4-week fetus, the endothelium of the sinusoid can hardly be recognized While its lumen is quite large. Many erythrocytes accompanied by their immature components can be seen among it. As to the 32-week fetal liver, the endothelium and Kupffer cell may be easily recognized but the lumen of the sinusoid dimenishes enormously. The hemopoietic foci are localized extra-sinusoidially and in close contact with liver cells. Their volume exceeds one half of the fetal liver lobule before the age of 28 weeks, then it dimenishes gradually. In the space of Disse a fat storage cell is revealed.4. The portal canal The mensenchyma and immature erythrocytes in the portal canal dimenishes with the increase of the fetal age. The portal canal is surrounded by the pigmented limiting plate cells of the liver lobules. The interlobular bile duct is differentiated from the limiting plate cells. Its epithelium is composed of both light and dark cells. The former is more numerous and contains many large mitochondria in its apical portion, while the latter shows higher electron density. Microvilli are located on the surfaces of both kinds of cells and finger like processes in the enlarged intercellular spaces are revealed.