Whole Mount Preparation of Mouse Intestine: Using a Simple Gut-incising Device to Prepare Whole Mount

This procedure uses a device consisting of the base that has high elevated strips at each end with grooves to take the rods and the lid. After harvesting the small intestine and colon from an adult mouse, hold the mesentery with curved forceps and gently pull the tissue away from the intestine to remove it. Place a Gilson-type pipette tip, cut at the wider end, onto a 10- or 20-milliliter luer fitting plastic syringe, and rinse the intestines with cold PBS.

After the tissue has been washed, lay out the small bowel and colon on a paper towel, and use scissors to divide the small bowel into three equal sections. Make several very small cuts in the intestinal segments to drain the fluid. Then, place another paper towel over the intestines and gently run a finger over the segments to squeeze out the remaining fluid.

Next, blot the preparations dry and gently insert stainless steel rods soaked in PBS into the tissues. Using a pencil, create labels for the segments including the autopsy date, experimental code, and animal identification number. Place the labels in the base of the device. Then, insert the rods and intestines into the slots at the base of the device, taking care that the proximal end of the segments are positioned in a standardized way near the labels.

Now, place the top piece of the device over the base, and use the angled bars to guide a scalpel blade longitudinally through the segments. To keep the tissue in place during the sectioning, carefully hold the segments with a finger so that they do not move with the knife.

After all of the sections have been made, remove the top of the device and use a piece of stiff card to carefully remove the filter paper and the tissues. Using a gloved fingertip dipped in PBS, slightly wet the segments. Gently roll the rod, side to side, to open up the gut and to spread the tissue flat.

The sections will adhere to the filter paper. After visually examining the preparations for any gross lesions, transfer the filter paper to a shallow bath of fixative. When the tissues are fixed, transfer them into 70% ethanol for storage until further downstream analysis.