Electron Microscopy of Mouse Tissues by Sandwich Freezing and Freeze-Substitution

Sandwich freezing is a method of rapid freezing by sandwiching biological specimens between two metal disks and has been used for observing exquisite, close-to-native ultrastructure of living yeast and bacteria after freeze-substitution. This method was also useful for preserving the clear and natural ultrastructure of glutaraldehyde-fixed microorganisms, cultured cells, and human tissues. In the present study, this method was used to observe the fine structure of animal tissues for the first time and succeeded in producing clear, exquisite images of mouse heart, liver, and pancreas ultrastructure. The high-quality images obtained in the present study demonstrate that this technique can be applied widely in the field of ultrastructure research.