Serial Sectioning Protocol

Serial sectioning is the procedure of collecting and mounting sections on a slide in the sequential order in which they were cut on the microtome. A ribbon refers to the sequence of connected sections pulled from the microtome.
Conventional tumor histopathological sections are generally sliced in parallel at certain interval distances, and this slicing method cannot effectively observe the growth characteristics of tumor tissue from inside to outside, and there is no continuity between individual slices, and continuous slicing to observe the three-dimensional whole tissue state cannot be realized.
Here, a method for making continuous pathological sections of tumor tissues is provided, aiming to solve the problem that traditional tumor tissue sections are not continuous and cannot observe the growth characteristics of tumor tissues from inside to outside.

Pretreatment. Fresh tumor tissues from animals were selected, and the fixative was infiltrated into the interior of the tissues by injection or perfusion method, and the dehydrating agent was selected to replace the water in the fixed tissues, and the transparent agent was used for transparent treatment.
Wax immersion and embedding. Paraffin wax is dipped into the tissue to replace the transparency agent; the wax-impregnated tissue is placed in the melted solid paraffin wax, and after the paraffin wax solidifies, the tissue is embedded to form a wax block.
Slicing. After trimming the wax block, the block is fixed and sliced using a vertical slicer or a circular slicer in concentric circles or in a spiral trajectory at any point along the outer edge surface of the block.
Spreading of slices. The slices obtained in the previous step were divided into different samples, and after the samples were numbered, the samples were laid flat on the surface of water at 40-45°C, and the slightly wrinkled samples were spreading naturally by the tension of water and the temperature of water.
Patching and baking. Place the samples on the slides sequentially according to the number and bake the slides to remove the remaining water.

The slicing knife must be sharp, with even force and slicing thickness of 3-5 microns. The slices are intact and free of contamination and wrinkles.
Large and small specimens must be handled separately, and the fixation time of large specimens must not be less than 6 hours; small specimens must not be less than 3 hours. The fixation solution must be replaced in time and must be rinsed under running water after fixation.
Gastroscopy, puncture and other small biopsy tissue sections must be made in continuous sections of not less than 8.

For research use only. Not for any other purpose.