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标题：Advantages and Disadvantages of in vitro Model Systems to set ADIs
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作者：Tracy D. Wilkins
期刊名称：Microbial Ecology in Health and Disease
印刷版ISSN：1651-2235
出版年度：2000
卷号：12
期号：1
DOI：10.3402/mehd.v12i1.8045
语种：English
出版社：Microbial Ecology in Health and Disease
摘要：In vitro implies a compromise over in vivo methods in science. Often that is the case, but when the in vivo experiment is in a rodent, the results can be as much of a compromise as a good in vitro system. That is the case with determinations of the effect of low levels of antibiotics on the intestinal flora of humans. The germ-free mouse associated with human flora is the best ‘in vivo’ system available, but the mouse intestinal tract differs from that of man almost as much as that of a cow. Like cows, wild mice derive nourishment from very complex plant materials and their intestinal tract is designed for this purpose. The front half of the stomach of rodents is lined with squamous epithelium instead of the secreting epithelium of the human stomach (and the posterior half of rodent stomachs). The purpose is to allow the rodent to consume large amounts of forage and store it in this chamber. Lactobacilli usually line this epithelium and lactic acid fermentation takes place. Even the secreting epithelium of the rodent stomach is often covered by a layer of yeast. These strains only exist in rodents and are even specific to rodent species. This is very different from the human where only Helicobacter can survive and live in the stomach. The large cecum of rodents is where our appendix is located. Our ancient ancestors evidently had a large cecum that allowed them to digest very slowly complex plant material, but as our diet changed to easily digestible material this was no longer needed. The rodent retains this dead-end sack and considerable fermentation takes place in this chamber. It is a continuous culture chamber in which the walls are lined with clostridia that live in the mucus layer and are only found in rodents.