This video provides a practical guide for handling and processing a fresh kidney biopsy specimen, typically obtained from a transplant patient. The procedure involves dividing the cylindrical tissue cores into samples suitable for three types of analysis: electron microscopy (EM), light microscopy (LM), and immunofluorescence (IF). For EM, tiny tips of the cores are fixed in glutaraldehyde. For LM, the cores must be wrapped in lens paper rather than standard sponges or bags to prevent distortion of the fresh tissue; a specific technique for folding the lens paper is demonstrated to aid the embedding process. Finally, the remaining core tissue is placed in Michel’s fixative for IF analysis.
Handling a Fresh Kidney Transplant Biopsy
0:14 Fresh Specimen Handling: Any specimen received fresh (unfixed) requires special attention; always ask why it arrived fresh. Standard handling procedures (e.g., immediate embedding) should be avoided.
0:44 Specimen Description: The biopsy typically consists of three small, tan-brown to yellow cylindrical soft tissue cores, approximately 0.6 to 0.8 cm in length.
0:57 Electron Microscopy (EM) Sample Preparation: The very small tips of each core are removed and submitted for EM analysis, focusing on capturing the glomeruli.
1:07 EM Fixation: The tips are placed in glutaraldehyde. Key Detail: Ensure a liberal amount of fixative is used, as glutaraldehyde does not penetrate tissue as rapidly as formalin.
2:36 Light Microscopy (LM) Sample Preparation: The remaining core tissue (two smaller cores are used in this demonstration) is prepared for LM.
2:41 Critical LM Technique: Do not use mesh bags or sponges for fresh tissue, as they will distort the sample. Instead, use lens paper for wrapping.
3:03 Lens Paper Folding Technique: The lens paper must be folded precisely: the corners should overlap rather than match up. After folding the ends, the entire assembly is rolled to create "bunny ears" (corners sticking out). This allows the embedder to pull the corners and open the paper like a cup without losing the small tissue sample.
3:57 Immunofluorescence (IF) Sample Preparation: The final remaining core is reserved for IF.
4:10 IF Fixation: The IF sample is placed in the original labeled container and submerged in Michel's fixative (transport medium).