Histo-LOOP: A Novel Embedding Tool for Standardizing, Simplifying, and Advancing Histological Tissue Preparation

Tissue preparation for paraffin embedding is a crucial step in histological processes. Standardized methods are required to ensure the accuracy of research and clinical diagnostic results. However, standardization is particularly challenging for long luminal tissues. Conventional methods such as single/serial sections and the Swiss roll, often have drawbacks including the risk of missing or misaligned sections, excess consumption of materials, and high workload. They also require significant expertise and are difficult to standardize. To address these issues, we developed the Histo-LOOP embedding tool-a novel tool designed to standardize, simplify, and improve histological processing. Histo-LOOP is suitable for various tissue types including long tubular tissue, allowing for a complete overview in cross-sectional and longitudinal views. It is also suitable for punch biopsies or small sections, and enables the assessment of multiple punch biopsies or sections within one paraffin block, and in multiple cutting planes, for example, for liver and prostate biopsies. Histo-LOOP does not interfere with the sectioning and staining process and does not cause artifacts.Here, we introduce the novel tool Histo-LOOP and describe preparation techniques for tubular tissue and small tissue samples using this tool, along with examples of their histological evaluation.