大鼠胚胎肝贮脂细胞超微结构的发育

ULTRASTRUCTURE OF THE DEVELOPMENT OF HEPATIC FAT-STORING CELL IN RAT EMBRYO

The ultrastructure of hepatic fat-storing cells in rat embryos was investigatedwith transmission electron microscope.It is considered that the rat fat-storingcells originate from mesenchymal cells.As the embryo develops,the fat-storing cell decreases in size gradully,this isespecially obvious at the time of birth.This may be related with the function of thistype of cell.In the hepatic fat-storing cell in embryo of 10 to 12 days,the roughendoplasmic reticulum has developed,the cell is rich in free ribosomes,and collagenfibrils may be observed in Disse's spaces.This indicates that the fat-storing cellshave possessed the function of synthesizing collagen.In embryo of 13 to 15 days,fat droplets appear in a few fat-storing cells and smooth endoplasmic reticulum, glycogen granules and pinocytosis may be seen at this time.It is suggested that thefunction of the uptake and storage of vitamin A may appear at that time too.There are desmosomes between the fat-storing cell and the hepatocyte.On the 16to 18 days,desmosomes are also present between the fat-storing cell and endothelialcell.This indicates that fat-storing cells are not free cells,but are bound to hepa-tocytes and endothelial cells via cellular junctions,At that time,microfilaments andmicrotubules are found in fat-storing cells,they are the skeleton of the cells andthey may be related to the regulation of the size of the sinusoids.In thedevelopment of embryo,the number of fat-storing cells and fat droplets have notincreased markedly,therefore,it is thought that they are increased after birth.