Selective killing of Paneth cells by intravenous administration of dithizone in rats.

Paneth cells are zinc-containing cells widely distributed in Lieberkühn's crypts of intestine in a variety of species. We found that rapid selective killing of Paneth cells took place after the intravenous (i.v.) injection of diphenylthiocarbazone (dithizone), a chelator forming a zinc dithizonate complex, in the rat. As soon as 5 min after the i.v. injection of dithizone, degeneration of Paneth cells occurred. At this stage, zinc dithizonate complexes were observed as purple-red granules in bright field microscopy. Thirty to 60 min later, Paneth cells were detached from the basement membrane and shed into the cryptic lumen. After 6 h, the cell debris in the crypts was no longer seen and the crypts once housing Paneth cells were now occupied by neighbouring crypt base columnar cells. Histochemically demonstrable zinc totally disappeared. After 12-24 h, however, definite Paneth cells began to resume. Histochemical staining for zinc was again positive at the apex of these cells. One week after dithizone administration, the number of Paneth cells increased twice as much as in uninjected control and histochemical staining for zinc was highly positive. After 2 weeks, Paneth cell hyperplasia subsided. X-ray microanalysis revealed that zinc was the most abundant metal in Paneth cells. We concluded that chelation of zinc and formation of zinc-dithizone complexes in Paneth cells' cytoplasm would be responsible for the selective degeneration observed after dithizone administration.