Ultrastructural Changes of Heart Muscle and Some Organells in Rats after Rapid Freezing / 第二军医大学学报

We report in detail ultrastructural changes and freezing damage mechanism about heart muscle and some organelles after rapid freezing. The ventricles of rat heart were cut pieces about 100-150/?m by microsiicer. The pieces were quickly injected liquid cryogen Freon 22 by Reichert-Jung spring-assistant mechanism (KF-80). The specimens frozen were rapidly transferred into substitution medium aceton and kept at -80℃(28h), then -60℃ (48h),-20℃(12h)and 4℃ (1 h). The structures of specimens frozen were well and there were no ice crystals in the area of the tissue frozen surface to 20?m depth. However, there were freezing damages in mitochondrial crista, intercellular substance and muscular fibre in the tissue surface to 30?m depth. The structure of tissue was destroyed by ice crystal over 50?m depth in the tissue. The results suggest that intercellular substance and mitochondrial crista are the most sensitive to ice crystal damage after rapid freezing of heart tissue, then the less sensitive are muscular fibre and nucleus. The unit membrane is not easy to be damaged by ice crystal.

Observation of Hepatocellular Ultrastructure and G-6-Pase Cytochemistry in Hepatocarcinogenesis Induced by Diethylnitrosamine in Rats / 第二军医大学学报

In the process of hepatocarcinogenesis induced by diethylnitrosamine (DENA) in rats, the hepatocellular ultrastructure and G-6-Pase reactions in hepatic nodes were observed by electron microscope. The results are as follows: As compared with normal hepatocytes, cell junctions were fewer, even disappeared in some areas and intercellular spaces were wider; in some cells, nuclear membranes invaginated into the nucleoplasms frequently, micleoli were enlarged, mitochondria appeared swollen and their cristae were scanty- and short, and depolymerized ribosomes dropped off the dilated rough endoplasmic reticulums; in some seriously diseased cells, nucleoli were enlarged, abundant free ribosomes were present, but the' other organelles were in lower differencial state. G-6-Pase reactions were positive before the 8th week of DENA induction and negative after the 12th week. These suggest the hepatocellular metabolic disturbance and low differenciation.