from the surface into the interior of the organoid (S3A Fig). In addition, we incubated sections with secondary antibody alone (after blocking) to assess the presence of nonspecific binding. We observed that the inner tissue region also gave rise to nonspecific antibody binding compared to the more superficial region (S3B Fig). Based on these data, we established a limit of 250 μm from the surface of the organoid for our further characterization.
