Concerning the nature of the cryosectioning process

Area of Science:

• Electron Microscopy
• Cryo-ultramicrotomy
• Biological Sample Preparation

Background:

• Cryosectioning is crucial for preserving cellular ultrastructure.
• Understanding potential artifacts during cryosectioning is vital for accurate interpretation.
• Freeze-drying is an inherent process during cryosectioning that requires careful consideration.

Purpose of the Study:

• To investigate the ultrastructural effects of intentional melting on frozen-thin-sections.
• To assess the presence of melting artifacts on cryosections prepared without chemical fixation.
• To evaluate the impact of freeze-drying rates on cryosection integrity.

Main Methods:

• Preparation of frozen-thin-sections of rat kidney using freon 22 without chemical fixation or cryoprotection.
• Analysis of cryosections using cross-sectioning and examination of surface morphology.
• Estimation of freeze-drying rates at different temperatures within the cryochamber.

Main Results:

• No melting artifacts were observed on the surface of frozen-dried and embedded cryosections.
• Cryosections exhibited distinct surface morphologies: one saw-toothed and the other smooth.
• Freeze-drying rates were quantified, indicating significant water removal during handling.

Conclusions:

• Frozen-thin-sections accurately represent the ultrastructure of frozen tissue.
• The observed surface features are likely due to freeze-drying rather than melting.
• Cryosections prepared without chemical fixation maintain ultrastructural integrity and chemical composition.