Functional anatomy of the enteric nervous system

Abstract

Congenital birth defects, of which Hirschsprung's disease is an example, are among the most difficult of illnesses to study in the human patients who suffer from them. By the time the condition is identified in an affected individual, the process that brought it about is over and done with. It is thus impossible to study the ontogeny of birth defects, such as Hirschsprung's disease, in a fetus while the problems develop. An investigator seeking to uncover the pathogenesis of such a condition must search, like a detective, for clues left behind by the perpetrator who has fled the scene of a crime. Even the identification of genes that may have mutated, important an achievement as that is, does not, by itself, explain why the defect develops. Human life, moreover, is so precious that human subjects are terrible laboratory animals. As a result, more can often be learned about the origins of human illness by studying animal models, than by investigating the patients themselves. Invasive research, which is only possible on animals, can be used to develop a conceptual framework to devise hypotheses that can subsequently be tested for applicability to human patients. Experiments, based on these hypotheses, can be targeted to what can be confirmed or denied by diagnostic tests or by analyzing the restricted materials available from human subjects. Human biology is thus made approachable by knowledge of animal biology. © 2008 Springer-Verlag.