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Concerning Germ-free Mice (GF Mice) / Germ-free Animal, Germ-free mice are functionally immature in the immune, endocrine, exocrine, respiratory and digestive systems
Mostly mice, born and reared in sterile environments from which no microbiota can be cultured
Germ-free (GF) mice are an important model system for understanding the impact of gut microbes on development and function of the Nervous System (N)
Germ-free animals are animals kept in isolators in the absence of living microorganisms
However, the sterile state in itself is not fatal
Germ-free animals possess a reduced number of immune cells within their intestinal lamina propria and exhibit smaller Peyer's patches compared to mice that are reared under conventional conditions.
Germ-free mice show underdeveloped gut-associated lymphoid tissues (GALT), a reduced count of intestinal lymphocytes, and lower levels of both antimicrobial peptides and immunoglobulin A.
Most of these deficiencies can be restored by introducing gut microbiota from animals raised under normal conditions.
Germ-free mice tend to be leaner, possessing about 40% less total body fat compared to mice housed under conventional conditions. When microbiota from conventionally housed mice are introduced to these germ-free mice, their body fat mass returns to normal levels within a span of two weeks.
In germ-free (GF) mice, invariant natural killer T (iNKT) cells accumulate in the colonic lamina propria and lung. This accumulation results in increased morbidity in models of inflammatory bowel disease (IBD) and allergic asthma.
When germ-free animals are given a complex gut microbiota, they develop mature immune systems
Isolated lymphoid follicles (ILFs) are absent. They generate T cell-independent IgA+ B cells.
Lavelle et al. 2010 Mucosal Immunology 3(1): 17-28
Germ-free mice exhibit underdeveloped lymphoid organs when there is an absence of any microbiota. Germ-free mice, lacking a microbiota, exhibit reduced innate immunocompetence, which results in increased susceptibility to infection. The specific types of T cells, like the pro-inflammatory Interleukin-17 Family / Interleukin-17 (IL-17)-producing Th17 cells, are uncommon.
Germ-free rodents kept in a protected, sterile environment and fed a controlled diet containing factors such as Vitamins (A11) usually supplied by the gut microbiota can survive significantly longer than conventionally reared animals
Germ-free mice show a lack of full development in their immune, endocrine, exocrine, respiratory, and digestive systems. As a result, they are particularly vulnerable to infections caused by pathogens.
While microbial colonization may not be essential for life, it is critical for health
Germ-free (GF) mice, which are reared without exposure to any live bacteria, ingest 30% more food compared with conventionally (CV) housed mice
Bernard S. Wostmann and his team made an intriguing discovery regarding germ-free animals. They found that these animals, despite consuming large amounts of nutrient-rich food, exhibited stunted growth and development when compared to their normal counterparts. The germ-free animals had smaller hearts, lungs, and livers, along with lower cardiac output. Additionally, they had thinner intestinal walls, reduced gastrointestinal motility, lower serum gamma globulin levels, and atrophied lymph nodes.
Systemically, they exhibit a diminished capacity for Antibody production, fewer plasma cells, smaller mesenteric lymph nodes, and reduced numbers of germinal centers versus their conventional counterparts
see also:
Germ-free Mice (GF Mice) / Germ-free Animal & Gut microbiota