Bz x100

Intestines were Swiss-rolled and fixed overnight in 4% paraformaldehyde at 4°C prior to processing and embedding. Sections were blocked with Blocking Buffer (1% BSA and 10% donkey serum in PBS) for 1 hour, 25°C, before staining with primary antibodies (Supplemental Table 1) at 1:200 overnight at 4°C followed by washing with PBS and staining with secondary antibodies at 25°C for 25 minutes. Finally, nuclei were counterstained with 1:10,000 DAPI and coverslips mounted with Prolong^® Gold Antifade Reagent. Duodenum, jejunum, and ileum were defined as the proximal, middle, and distal third of the small intestine. Proximal colon was defined as the proximal 4cm of the large intestine, and distal colon as the distal 4cm. For alkaline phosphatase staining, we used the Vector^® Red Substrate Kit, Alkaline Phosphatase (Vector Laboratories SK-5100) on deparaffinized slides as described in the manufacturer’s protocol. TUNEL was detected using the Click-iT^™ Plus TUNEL Assay for In Situ Apoptosis Detection, Alexa Fluor^™ 594 dye (Thermo Scientific C10618). All stains were imaged on the Keyence BZ-X100.