Morphological Evidence for the Transport of Dehydrocholic Acid in the Hepatocyte as Revealed by Freeze Fracture Replica

급속동결할단법에 의한 간세포내 Dehydrocholic Acid 수송에 관한 형태학적 관찰

The pathway of intracellular transport of dehydrocholic acid was investigated in the hepatocytes of rats by transmission electron microscopy with conventional and freeze fracture methods. Both in normal and experimental groups, the cis Golgi cisterns were sacculated and faces toward the bile canaliculus. In the experimental group, however, the cis Golgi cisterns showed buds, which were probably separated to be vesicles. Some of the buds were connected to the cisterns with the narrow neck. The vesicles were increased in the vicinity of bile canaliculi. The fusion between vesicles and bile canaliculus were frequently observed in the experimental group. This was particularly well shown in the freeze fracture replica. In the thin section, the vesicles were devoid of visible contents as seen in the bile canaliculli. The evidence suggests that the vesicles are derived from the cis Gogi cistern in the way that buds pinch off, serve as vehicles to transport dehydrocholic acids and fuse to bile canaliculi for exocytosis.

본 연구에서는 박절편과 동결할단복제법을 이용하여 흰쥐 간세포에서 dehydrocholic acid가 수송되는 경로를 전자현미경적으로 조사하고자 하였다. 정상군이나 dehydrocholic acid 투여군에서 대부분의 Golgi 장치는 형성면을 담세관으로 향하고 있었다. Dehydrocholic acid 투여 20분 후에 세포질내세망과 Golgi 장치 및 소포 등이 담세관 주위에 증가되어 있었는데 특히 Golgi 장치 형성면에서는 소포가 될 것으로 추정되는 싹이 돌출되어 있었으며 소포들은 담세관에 융합된 것들도 관찰되었다. 이러한 소견으로 미루어 담즙산의 분비는 Golgi 장치 형성면의 쌀이 유리되어 형성된 소포가 담세관막에 융합되므로서 이루어질 것으로 추정된다.