Distribution of Cajal like cells and innervation in intrinsic ureteropelvic junction obstruction.

C-kit positive interstitial cells of Cajal (ICC)-like cells are defined as pacemaker cells in the ureter, which produce and coordinate peristaltic motility. To investigate the changes in ICC-like cells and innervation in segments of intrinsic uretero-pelvic junction (UPJ) obstruction.Full thickness specimens obtained from UPJ segments (n = 77) were divided into 3 groups. Group I included 32 intrinsic UPJ obstruction segments, separated into 3 subgroups: Group Ia (proximal), Group Ib (obstruction, intermediate) and Group Ic (distal segments). Group II included 30 normal UPJ segments derived from the nephrectomy specimens. In Group III, 15 UPJ segments of chronic obstruction were analyzed. Formalin fixed, paraffin embedded specimens from UPJs were analyzed immunohistochemically for CD117, S100 and synaptophysin protein expression in nerve plexus and ganglionic cells in the neuromuscular junction.Group Ib showed significantly decreased (p < 0.05) positive staning with c-kit protooncogene protein (CD117), S100 and synaptophysin proteins compared with Group Ia and Group Ic. ICC-like cells were observed in increased number (p < 0.05) in Group Ia compared to Groups II and III. Group Ib had lower synaptophysin positivity compared to Group II.The findings support the hypothesis of decreased innervation in the etiopathogenesis of intrinsic UPJ obstruction. Increased number of ICC-like cells in Group Ia suggests that peristaltic activity is higher in pelvicalyceal region.