对胎儿肝脏的冷冻复型电镜观察

STUDIES OF THE HUMAN FETAL LIVER——FREEZE-FRACTURE ELECTRON MICROSCOPIC OBSERVATION

本文应用冷冻复型电镜技术,对6例不同胎龄的胎儿肝脏进行了观察。发现肝细胞膜的膜内微粒,随胎龄增长由均匀变为不均匀;肝细胞的狄氏间隙面和胆小管腔面的微绒毛由少而多;缝管连接仅见于两肝细胞相邻面,未见桥粒。紧密连接仅见于几个肝细胞间的胆小管四周;肝细胞核每μm^(2)上的核孔数及其所占核表面积随胎龄增长而加大。核孔直径范围为67~100 nm。胞质内有丰富的细胞器,如成层排列的粗面内质网、清晰的高尔基复合体、成群存在的小泡小管状滑面内质网以及许多圆形线粒体等,它们与胎龄的增长无明显关系。肝血窦内皮筛板区有成群分布、大小不等的内皮孔,12、28、32、40周者,每μm^(2)上分别为4、12、19、25个,其所占测算区表面积依次为5、8、10、31%;内皮孔直径为81~125 nm。在胞质多的内皮细胞突上无孔,但有吞饮泡。细胞核核孔稀少。内皮外无基膜,其与贮脂细胞和星状细胞间未见连接装置。狄氏间隙随胎龄增长由小变大,其间微绒毛由少至多,造血灶于32周前普遍存在。以上各细胞膜的PF面膜内微粒均较EF面多,尤以肝细胞者最多。

The structure of 6 human fetal livers,at the age of 12-40 weeks,were studied electron microscopically by the method of freeze-fracture replica.The results were as follows:1.The cell membrane of various parts of the liver cell at different fetal age varies with one another;gap junction may only be revealed on the appositional surfaces of adjacent liver cells,desmosome is not observed;tight junction only occurs around bile canaliculi.The organelles in the hepatocytes are abundant,no obvious difference is observed at various fetal age;nuclear pore like structure can be shown on the RER,but is not revealed on the cisterna of Golgi complex.The mean number of the nuclear pores on the nuclear membrane of the liver cells at 12,20,28,32,40,week fetus is 10,14,16,11,14 per μm^(2) respectively.The mean diameter of the pores varies in 67-100nm and the space from center to center is 100-500 nm,the area possessed by them is 4,5,8,9,10%of the nuclear surface respectively.2.The endothelial pores are only present on the"sieve plates",while pinocytotic vesicles occur in the cytoplasmic processes,the average number of the pores and the area occupied by them increase with the fetal age,rare nuclear pores occur on its nuclear membrane.There is no basement membrane outside the endothelium.Junctional complex is not observed neither between endothelial cell and Kupffer cells nor between endothelial cell,hepatocytes and fat-storing cell.Intramembrane particles on the PF of various cell membranes are much more than on the EF,it is relatively more numerous on the liver cell than other cells.