Geometric morphometric analysis of plastinated brain sections using computer-based methods: Evaluating shrinkage and shape changes

Background

Plastination preserves biological specimens for long-term and geometric morphometry analyzes shape differences with advanced statistical methods. This study primarily aimed to statistically quantify shrinkage in brain sections following plastination. The secondary goal was to present the shrinkage occurring in both tissues and cavities of specific anatomical structures using geometric morphometry.

Methods

Fourteen sections from each of nine male bovine brains underwent silicone plastination using the standard technique, which involves four stages: fixation, dehydration, forced impregnation, and curing. The shrinkage percentage in plastinated sections was measured using ImageJ, while geometric morphometry was used for shape analysis. Correlation analysis was performed to reveal the relationship between ventricle area and shrinkage percentage.

Results

Significant shrinkage was observed in each brain section. A positive correlation was observed between the shrinkage on the sections and ventricular area. However, with the exception of sections number 2, 5, 9, 12 and 13, this correlation was not statistically significant for the remaining sections. Using geometric morphometric, shrinkage, and associated shape variations in specific anatomical regions within the serial brain sections were illustrated with visual graphics. Shape analysis revealed the most pronounced shrinkage in the sulcus coronalis, sulcus suprasylvius rostralis, ventral surface of the thalamus, and the third ventricle. Additionally, the cornu ammonis (hippocampus) exhibited the most significant shrinkage and shape variation. While morphometric analyses did not reveal significant shrinkage in cavity-like structures, geometric morphometric analyses demonstrated significant shrinkage in the third ventricle.

Conclusions

This study is unique in that it is the first to comprehensively demonstrate, using geometric morphometry, the morphological changes that occur in brain tissue during plastination. The findings, when combined with graphical and statistical data analysis, emphasize the effectiveness of geometric morphometry as a powerful tool for elucidating shape changes in plastination research.