Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 4/1/2008
Publication Date: 8/16/2011
Citation: Burrin, D.G. 2011. Trophic Factors and Regulation of Gastrointestinal Tract and Liver Development. In: Polin, R.A., Fox, W.W., Abman, S.H., editors. "Fetal and Neonatal Physiology". 4th edition. Philadelphia, PA: Saunders Publishers. p. 1-7.
Technical Abstract: In order to understand the role of trophic factors in fetal and neonatal gastrointestinal and liver growth it is important to first consider the nature of growth. The fetal and neonatal period is the most dynamic period of post conceptual growth and includes critical developmental milestones, such as gastrulation, organogenesis, morphogenesis, cellular differentiation and functional maturation, all of which are described in detail in other chapters in this section. In the case of the intestine, this includes formation of the gut tube, the appearance of villi and digestive enzymes, and the development of swallowing and mature motility patterns. Growth at the tissue and cellular level is characterized by increased cell numbers, i.e., hyperplasia, and increased cellular size, i.e., hypertrophy. Intestinal growth also involves expansion of the number and size of crypt and villus units. Moreover, the timing and characteristics of fetal and neonatal GI and liver growth are exquisitely coordinated with the events of birth and weaning to ensure survival of the organism. The regulation of the timing and nature of GI and liver growth is complex and involves multiple and often redundant factors. Among these factors are intrinsic cell programs or signals arising from gene expression, as well as extracellular signals, such as peptide growth factors, hormones, nutrients, and microbes, which originate from surrounding cells, the blood and the gut lumen.