Background: Preparation and processing of free-floating histological sections involve a series of steps. The amount of labor, particularly sectioning and mounting, quickly multiplies as the number of samples increases. Embedding tissue samples in a flexible matrix allows simultaneous handling of multiple samples and preserves the integrity of the tissue during histological processing. However, aligning multiple asymmetrical samples, for example small-animal brains, in a particular orientation requires skillful arrangement and securing of the samples by pinning onto a solid surface. Consequently, costly technical services offered by contract research organizations are often sought.
New method: An improved approach to align and embed multiple whole or half rodent brain samples into a gelatin-based matrix is described. Using a template specifically designed to form arrayed mouse brain-shaped cavities, a "receiving matrix" is prepared. Inserting brain samples directly into the cavities allows the samples to be effortlessly positioned into a uniform orientation and embedded in a block of matrix.
Results: Multiple mouse brains were arrayed in a uniform orientation in a gelatin matrix block with ease using the receiving matrix. The gelatin-embedded brains were simultaneously sectioned and stained, and effortlessly mounted onto glass slides.
Comparison with existing methods: The improved approach allowed multiple whole or half mouse brains to be easily arrayed without pinning the samples onto a solid surface and prevented damages or shifting of the samples during embedding.
Conclusions: The new approach to array multiple brain samples provides a simple way to prepare gelatin-embedded whole or half brain arrays of commercial quality.
Keywords: Brain array; Embedding; Frozen-section; Gelatin; Immunohistochemistry; Matrix; Tissue preparation.
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