Comparison of the Fixation Effects of Six Composite Fixatives on Retinal Tissue of Golden Hamsters

Objective To compare the effects of six composite fixatives on paraffin sections of golden hamster retinal tissue, and to optimize the fixation methods for retinal tissue paraffin sections of golden hamsters. Methods Eighteen male SPF grade golden hamsters were taken and randomly divided into six groups of three animals each. After each animal was anesthetized by intraperitoneal injection of sodium pentobarbital, cardiac perfusion was performed using 4% paraformaldehyde, Bouin's, Carnoy, Davidson's, Zenker, and Helly fixatives, respectively. The eye tissues of each animal were taken out to make eye cups and put into the corresponding compound fixative solution for fixation, and then taken out for paraffin embedding after 48 h. The embedded blocks were sliced using microtome, and then stained with hematoxylin and eosin (HE). The morphological characteristics of retinal tissue cells were observed under a light microscope and scored in a double-blind method to statistically analyze the fixation effect and staining quality of various composite fixative solutions.ResultsRetinal sections fixed with Davidson's fixative exhibited intact morphology without breaks, clear structural layers, well-morphosed nuclei, and tight adhesion between the retina, sclera, and uvea. In contrast, sections fixed with 4% paraformaldehyde, Bouin's, and Carnoy fixatives showed varying degrees of retinal breaks and detachment from the sclera. Sections fixed with Zenker and Helly fixatives demonstrated the poorest quality, characterized by pronounced detachment, large fissures, unclear cell layers, and pale staining. Statistical analysis using SPSS 27.0 software revealed significant differences in mean scores among the six fixatives (P<0.001). The fixation quality ranking was as follows: Davidson's fixative > 4% paraformaldehyde > Bouin's fixative > Carnoy fixative > Helly fixative > Zenker fixative. Zenker and Helly fixatives showed significantly lower scores than the other fixatives (P<0.001), while no significant differences were observed among the remaining fixatives (P>0.05). Conclusion Davidson's fixative provides the best fixation and staining results, followed by 4% paraformaldehyde and Bouin's fixative. Carnoy fixative exhibits suboptimal performance, while Zenker and Helly fixatives result in the poorest outcomes. Therefore, Davidson's fixative is recommended as the optimal fixative for golden hamster retinal tissue, with 4% paraformaldehyde, Bouin's and Carnoy fixatives as alternative options.