Alterations of mouse lung tissue dimensions during processing for morphometry: a comparison of methods

Area of Science:

• Histology
• Stereology
• Morphometry

Background:

• Accurate morphometric studies require preserving original tissue dimensions.
• Tissue shrinkage during histological processing can compromise stereological calculations.
• Unbiased stereology necessitates minimizing dimensional alterations in histological samples.

Purpose of the Study:

• To investigate tissue dimension changes in mouse lungs during histological processing.
• To evaluate the impact of different fixatives and embedding protocols on shrinkage.
• To identify optimal methods for preserving lung tissue dimensions for stereological analysis.

Main Methods:

• Mouse lungs were fixed using 4% formalin or a 1.5% glutaraldehyde/1.5% formaldehyde mixture.
• Tissue blocks were processed using stereological principles for embedding in paraffin or glycol methacrylate.
• Dimensional changes were assessed using stereological measurements of tissue cut faces.

Main Results:

• Paraffin embedding resulted in approximately 40% shrinkage of cut face areas.
• Simple glycol methacrylate embedding caused around 30% shrinkage.
• Embedding in glycol methacrylate after osmium tetroxide/uranyl acetate treatment showed <3% shrinkage.
• Glutaraldehyde-containing fixatives demonstrated superior shrinkage reduction.

Conclusions:

• Embedding mouse lung tissue in glycol methacrylate with prior osmium tetroxide and uranyl acetate treatment is recommended.
• This method significantly minimizes shrinkage, ensuring unbiased stereological estimates.
• Using a glutaraldehyde-containing fixative further enhances dimensional preservation.