Interstitial Cajal-like cells in human gallbladder.

We describe here an interstitial Cajal-like cell type (ICLC) in human gallbladder, resembling the archetypal enteric interstitial cells of Cajal. Gallbladder ICLC were demonstrated in fresh preparations (tissue cryosections) using methylene-blue, and fixed specimens in Epon semi-thin sections stained with toluidine blue or transmission electron microscopy (TEM). The positive diagnosis of gallbladder ICLC was further verified by immunohistochemistry: CD117/c-kit, CD34, and another 16 antigens: vimentin, desmin, nestin, alpha-smooth muscle actin, NK-1, S-100, PGP-9.5, tau protein, chromogranin A, NSE, GFAP, CD1a, CD62-P, CD68, estrogen and progesterone receptors. Double immunostaining was performed for CD117, CD34 and CD117 and nestin, respectively. In fresh specimens, the spatial density of gallbladder ICLC was 100-110 cells/mm(2). ICLC mainly appeared beneath the epithelium and in muscularis (about 7%, and approximately 5%, respectively). In toto, ICLC represent in gallbladder approximately 5.5% of subepithelial cells. TEM showed that diagnostic criteria were fulfilled by ICLC. Moreover, TEM indicated that the main ultrastructural distinctive feature for ICLC, the cell processes, develop into the characteristic shape at a relatively early stage of development. It remains to be established if, in humans, ICLC are involved in gallbladder (dis)functions (e.g. pace-making, secretion (auto-, juxta- and/or paracrine), intercellular signaling, or stone formation).