Development
of the newborn GI tract and its relation to colostrum/milk intake:
a review.
Xu RJ.
Department of Zoology, University of Hong Kong, Hong Kong.
During the immediate postnatal period, the gastrointestinal (GI) tract
undergoesprofound growth, morphological changes and functional maturation.
The oesophagus shows an accelerated cell proliferation in the epithelium
and an increased production and accumulation of mucus in the glands.
The stomach shows a rapid tissue growth and a marked increase in acid
secretion capacity. The intestine shows increased tissue growth and
marked epithelial modifications; the latter include the loss of the
ability by the epithelial cells of the small intestine to absorb macromolecules,
and the loss of the ability by the epithelial cells of the large intestine
to synthesize digestive enzymes and to absorb amino acids and glucose.
These changes are apparently related to the onset of colostrums ingestion,
because starved or water-fed newborns showed little changes in the
GI tract. A number of hormones and growth-promoting peptides, such
as insulin, cortisol, epidermal growth factor (EGF) and insulin-like
growth factor I (IGF-I), have been found at high concentrations in
the maternal colostrum. There is evidence that colostrum-bone EGF
and IGF-I play a role in postnatal GI development in newborns. The
role of othercolostrum-borne hormones and growth-promoting peptides
remains to be assessed. Further studies are also required to demonstrate
if colostrum-borne EGF and IGF-I can be used therapeutically to those
newborns with immature or diseased GI tract, such as in cases of premature
birth or prenatal growth retardation or cases requiring total parenteral
nutrition.
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