VISUALIZATION OF INTERSTITIAL-CELLS OF CAJAL IN THE MOUSE COLON BY VITAL STAINING

Interstitial cells of Cajal (ICCs) are believed to be a major element in generating the spontaneous rhythm of the gastrointestinal tract. A prominent problem in the study of these cells has been the difficulty in observing them in intact tissues. We used the lipophilic dye DiI to stain ICCs in the submucosal-circular muscle border of freshly dissec ted mouse colon. The placement of small DiI crystals in this area resu lted in the labeling of ICC-like cells. Two main morphological cell ty pes, viz., bipolar and multipolar, were noted. Bipolar cells had two p rimary processes emerging from the poles of an elongated soma. The mea n length of these processes was 78.7 mu m. These cells constituted 42. 3% of the sample (n=105). Multipolar cells (54.3% of total) had a less elongated soma and extended 3-6 main processes whose mean length was 56.3 mu m. These processes showed no preferred direction. The length o f the primary processes of bipolar cells was 40% greater than that of multipolar cells (P<0.02). Three cells (2.9%) had only one primary pro cess. The DiI stain could be converted into a stable electron-opaque p roduct. Electron-microscopic observations showed that these cells had the typical appearance of ICCs reported in previous studies. This stai ning method should be useful for physiological investigations of ICCs in gastrointestinal tissues.