Self-organized patterning of peristaltic waves by suppressive actions in a developing gut.

Gut peristalsis is a wave-like movement of a local contraction along the gut, and plays important roles in nutrient digestion and absorption. When peristaltic waves emerge in embryonic guts, randomly distributed origins of peristaltic waves (OPWs) become progressively confined to specific sites. We have investigated how this random-to-organized positioning is achieved using the caecum as a model in chicken embryos. While prominent OPWs, recognized as active (spontaneous) contractions, are located at endpoints of the intact caecum, other regions are also found to possess latent rhythm unveiled by fragmentation of a caecum into pieces, showing that the latent rhythm is normally suppressed in the intact gut. Analyses with caecum fragments demonstrate that the latent rhythm is spatially patterned in an early gut, to which negative impact by primitive passing waves contributes; the more passing waves a region experiences to undergo forced/passive contractions, the slower latent rhythm this region acquires. This patterned latent rhythm underlies the final positioning of OPWs at later stages, where a site with faster latent rhythm dominates neighboring slower rhythm, surviving as a "winner" by macroscopic lateral inhibition. Thus, the random-to-organized patterning of OPWs proceeds by self-organization within the caecum, in which two distinct mechanisms, at least, are employed; suppressive actions by primitive waves followed by macroscopic lateral inhibition.