part of gastrointestinal tract interstitial cell of Cajal BTO:0003914 BrendaTissueOBO ICC cell Pleomorphic cells having an oval nucleus and long, branching cytoplasmic processes that interlace with processes of adjacent cells, interspersed between the circular and longitudinal muscle layers of the gastrointestinal tract and in the smooth muscle of the esophagus; they are thought to act as pacemakers. interstitial cell