An inexpensive device for freeze drying and plastic embedding tissues at low temperatures

Area of Science:

• Electron Microscopy
• Cell Biology
• Biotechnology

Background:

• Preserving the native state of biological tissues is crucial for accurate ultrastructural analysis.
• Traditional methods can introduce artifacts, altering the localization of ions and molecules.
• Rapid freezing techniques aim to minimize structural damage during sample preparation.

Purpose of the Study:

• To describe a custom-built device for freeze-drying and low-temperature resin embedding of biological tissues.
• To evaluate the effectiveness of rapid freezing and freeze-drying in preserving cellular integrity and molecular localization.
• To present freeze-dried cartilage as a case study for the described methodology.

Main Methods:

• Biological tissues were rapidly frozen using liquid propane.
• A custom freeze-drying device with a liquid nitrogen-cooled stage was employed to prevent ice recrystallization.
• Vacuum embedding in low-temperature resin (Lowicryl) and in situ polymerization were performed.
• The method was applied to cartilage tissue preparation for electron microscopy.

Main Results:

• The freeze-drying process resulted in minimal ice damage to chondrocytes.
• Intracellular organelles within the cartilage tissue were clearly visualized.
• The method demonstrated effective preservation of tissue ultrastructure.

Conclusions:

• The described rapid freezing and freeze-drying technique offers a pragmatic alternative to cryosectioning for electron microscopy.
• This method effectively preserves the native localization of ions and molecules in biological tissues.
• Further investigation is needed to fully elucidate the potential translocation of labile elements like Na and K.