Gastrointestinal Tract - Postnatal
This page is an introduction to postnatal gastrointestinal tract development. This nutritionally involves a change from prenatal placental vascular nutrition to postnatal oral colostrum/milk enteral nutrition (enteral = nutritient delivery as fluid into the gastrointestinal tract). Also look at the topic of Milk in relationship to neonatal nutrition. The postnatal gastrointestinal tract development is also about increased activity of the tract and associated organs as well as the populating with intestinal flora in the tract. This is also the pathway for initial passive immunity through absorption of maternal immunoglobulin from breast milk.
Some Recent Findings
Small Intestine Length
Small intestine growth in length prenatally is initially linear during the first half pregnancy (to 32 cm CRL), followed by rapid growth in the last 15 weeks doubling the overall length.
Postnatally, growth continues rapidly but after 1 year slows again to a linear increase to adulthood.
|Age (weeks gestational age)||Average Length (cm)|
|1 year postnatal||380|
Table data based upon 8 published reports of necropsy measurement of 1010 guts.
- Links: Intestine Development
Lipids present in the intestine leads to a reduction in nutrient intake. Recent research has shown that lipids present in the intestine can also regulate endogenous nutrient production.
Signalling pathway: presence of ingested lipids - intestinal lipid sensors - signal to the brain - liver - reduction in endogenous glucose production
Insulin-like Growth Factors
Some evidence to suggest that in preterm infants IGFBP-2 and IGF-II present in breast milk may have an important role in their early development.
- insulin-like growth factors (IGFs) and IGF binding proteins (IGFBPs)
Gut Microorganism Population
The normal newborn gastrointestinal tract contains little if any microorganisms (commensal intestinal microbiota, microbiota, flora, microflora).
Postnatally, the tract has to be populated by microorganisms, which are mainly anaerobic bacteria and then aerobic bacteria, but may also include yeast and fungi. The foregut comparatively has few microorganisms when compared to the midgut and hindgut.
There are several infectious pathogens that can populate the postnatal gut leading to a number of different diseases: Escherichia coli (enterotoxigenic), Shigella (a gram-negative, non-spore forming rod-shaped bacteria infectious through poor hygeine and ingestion, fecal–oral contamination. More? Dysentery), Vibrio cholerae and Listeria.
Antibiotics - Treatment of other neonatal infections systemically with antibiotics can alter the bacterial population.
Cartoon showing relationship between microbiota and intestinal functionCite error: Closing
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| Mouse model analysis of colonic microbiota. Mice with NEC (a) are compared to mice without NEC (b). * indicates statistically significantly more in mice with NEC. ** indicates statistically significantly more in mice without NEC.
- Restricting microbial exposure in early life negates the immune benefits associated with gut colonization in environments of high microbial diversity http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0028279
- <pubmed>21445365</pubmed>| PLoS One.
- <pubmed>1752463</pubmed>| PMC1379160 | Gut.
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Search Pubmed Now: postnatal gastrointestinal development
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Cite this page: Hill, M.A. (2019, September 16) Embryology Gastrointestinal Tract - Postnatal. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Gastrointestinal_Tract_-_Postnatal
- © Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G