CD34 AND C-KIT IMMUNOREACTIVE CELLS IN THE HUMAN EMBRYONAL AND FETAL SMALL BOWEL

Interstitial cells of Cajal (ICC) play important roles in the control of digestive motility: they generate the electrical slow-wave activity (pacemaker component) of the gut musculature and are involved in neurotransmission and stretch sensation. ICC expresses c-kit and depends on signaling via Kit receptors for development and maintenance of phenotype. The aim of the present study was to investigate if the c-kit immunoreactive (IR) cells present in the wall of the small bowel at the beginning of the fetal period are CD34 immunopositive. Human small bowel specimens were obtained from 5 embryos and 7 foetuses, 7–12 weeks of gestational age. The specimens were exposed to anti-c-kit antibodies to investigate ICC differentiation and anti-CD34 antibodies to identify presumed ICC progenitors. The differentiation of smooth muscle cells was studied with anti-desmin antibodies. At 9–10 weeks, c-kit IR cells were present in the wall of small bowel in the form of a narrow band of cells, at the level of the myenteric plexus, but they were absent in the mucosa and submucosa of the gut. At the same time, CD34 IR cells were present at the level of submucosa and mucosa, and they were not present in the outer parts of gut wall. A clear distinction between the localization of c-kit IR cells and CD34 IR cells was evident. We may conclude that c-kit IR cells present in the small bowel wall at the beginning of fetal period of development, at 9–10 weeks, do not exhibit concurrent CD34 immunoreactivity.Key words: Small bowel, c-kit, CD-34, immunohistohemistry, huma