The crypt cycle in mouse small intestinal epithelium.

We have used a mutation-induced marker system in the intestine of mice heterozygous at the Dlb-1 locus, which determines the expression of binding sites for the lectin Dolichos biflorus agglutinin, and the frequency of clustering of mutated crypts with time as a means of investigating the frequency of the crypt fission process and the crypt cycle. Whole-mount preparations from heterozygous Dlb-1b/Dlb-1a mice were stained with a peroxidase conjugate of Dolichos biflorus agglutinin. Mutations at the Dlb-1b locus in crypt stem cells result in loss of DBA-Px binding in these cells and subsequently their progeny, which eventually results in a rare isolated single, unstained crypt. The subsequent development of pairs, triplets and clusters of negative staining crypts has been assumed to be the result of crypt fission. The frequency of these fission events has been measured in control untreated mice. These negative crypts are the result of spontaneous mutations. We have also looked at mutated crypts after treatment with N-nitroso-N-ethylurea or N-methyl-N'-nitro-N-nitrosoguanidine of young adult mice, which elevates the number of mutations. Our results suggest that the crypt cycle in control animals is very long, 187 +/- 44 weeks (3.6 years, i.e. essentially the life of a laboratory mouse). This implies that about a third of the crypts may divide once in the life of a mouse. After sufficient time for conversion of mixed crypts to monophenotypic crypts after mutagen treatment several clusters of negative crypts were seen.(ABSTRACT TRUNCATED AT 250 WORDS)