Tissue Processing and Sectioning

Tissue processing is a crucial step in preparing biological specimens for microscopic analysis. It involves several stages to ensure that tissue is adequately preserved and hardened, so that thin sections can be created for examination under a microscope. Initially, fixation is employed to preserve tissues using chemicals such as formalin or neutral buffered formalin, which stabilize the tissue structure and prevent decay.


Here is a brief overview of the processing stages:


  • Dehydration: Tissues are typically dehydrated in a series of ethanol baths of increasing concentration. This step is essential to remove all water from the tissue sample.
  • Clearing: After dehydration, the tissue is cleared in a substance such as xylene, which prepares the tissue for infiltration by displacing the alcohol.
  • Infiltration: The cleared tissue is then infiltrated with a medium like paraffin wax or plastic resin to support the delicate tissue structure during sectioning.
  • Embedding: Following infiltration, tissues are embedded into a block of the chosen medium to provide stability.


Once the specimen is embedded, sectioning can begin. This involves using a microtome, a precision instrument used to cut very thin sections of tissue. Depending on the type of tissue and the analysis required, either paraffin or plastic resin blocks can be used. Paraffin is more common for routine histology, but plastic resin provides better support for harder tissues. For cryosectioning, tissue may be embedded with optimal cutting temperature (OCT) compound or gelatin.


In sectioning, the microtome blade slices the block to produce sections often only a few micrometers thick. These sections are then mounted onto slides for staining and analysis.


Each step, from fixation to sectioning, is tailored to ensure that the tissue's microscopic structure is well-preserved and that the finest details can be discerned under microscopic inspection.

Why building a liver is like solving a 3D puzzle—and how MTM Laboratory researchers are finally cracking the code

November 27, 2025
Recent advances in biofabrication are revolutionizing liver tissue engineering by enabling precise spatial patterning of liver cells to mimic the organ’s complex architecture. Techniques like 3D bioprinting, microfluidics, and self-assembled cell aggregates help recreate critical features such as metabolic zones, cell polarity, and vascular networks. These engineered liver models improve drug testing, disease research, and hold promise for regenerative therapies. Despite challenges in scaling and standardization, integrating multiple fabrication methods and emerging technologies like machine learning are driving progress. Ultimately, these innovations bring us closer to creating functional liver tissues for clinical and pharmaceutical applications. See full article here.

October 18, 2025
𝗦𝗶𝗺𝗽𝗹𝗲 𝗦𝘂𝗺𝗺𝗮𝗿𝘆: This study explores how we can improve lab-grown liver cells for medical research and drug testing. The MTMLab team works with induced pluripotent stem cells (iPSCs) - special cells that can be transformed into liver-like cells - because real human liver cells are hard to obtain. However, these lab-grown liver cells don't function as well as mature adult liver cells. The research team discovered that the surface environment where these cells grow is crucial for their development. We created tiny fiber scaffolds made from different materials like collagen, decellularized livers, and chitosan that mimic the natural structure around liver cells. When liver cells were grown on these specially designed nanofibers for three weeks, they displayed higher function compared to cells grown on standard surfaces. Our key finding was that both the material composition and the nanoscale fiber structure were important - stiffer synthetic fibers or softer materials without the appropriate topography or composition prevented proper cell maturation. This research helps create better lab models of human liver tissue that can be used for testing new drugs and studying liver diseases more effectively.

2025 BMES Annual Meeting - MTMLab Member Presentations!

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Owen Lally Modeling the synergistic effects of alcohol and fats on liver disease via engineered cocultures In Vitro Liver Toxicology Testing of Rat and Dog Hepatocytes to Reduce In Vivo Regulatory Requirements Nathan Shelton Enhancing the Functions and Hepatitis B Virus Infectability of Primary Human Hepatocytes Protein Microarrays to Probe Synergistic Effects of Extracellular Matrix Composition and Stiffness on Liver Macrophages Lesly Villarreal Engineering a 3D Placental Trophoblast Invasion Platform Via Droplet Microfluidics Gas-permeable Plates to Model Synergetic Effects of Oxygen and Endothelial Factors on Liver Zonation Emanuele Spanghero Modeling the Interplay Between Liver and Heart Diseases via a Human Dual-Organ Platform Engineering High Cell Density Beating Cords of Cardiomyocytes and Fibroblasts via Photopatterned Alginate