The growth and differentiation of the intestinal epithelium is a paradigm for the development of mature columnar cells from undifferentiated precursors. Little is known about growth regulation, although evidence for circulating hormones, and paracrine growth factors, are becoming more plentiful. The transcriptional events leading to the production of lineage-specific markers appear to be mediated by tissue-specific nuclear factors, often induced along the differentiation pathway. Molecular analysis of intestine-specific gene products help further our understanding of the functions for such proteins as trefoil peptides, mucins, laminins, and brush-border hydrolases. To understand which processes during gut morphogenesis and programmed cell growth represent key regulatory steps, molecular genetic systems are being considered to help identify and characterize the specific genes involved.
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