Grading of pit structures in the colorectal mucosa of patients with inactive UC. MCS grade 1: pits small, round, and regularly arranged (a). MCS grade 2: pits rather large, oval, and somewhat irregular in arrangement (b). MCS grade 3: pits of various shapes and sizes and irregularly arranged (c). MCS grade 4: dispersed pits varying in morphology associated with the presence of small erosions (d).