The benefits of utilizing laboratory mice include low cost, ease of maintenance, and accessibility of molecular tools. However, the ages of experimental mice in the literature vary drastically. We hypothesized that there exists age-related variation in the murine small intestine across developmental stages. Segments of small intestine were harvested from C57BL/6J mice of varying ages (E17 to 24 weeks; = 3–4/group). Slides were analyzed for morphometric parameters, cell types, and crypt proliferation index (CPI). Secondary analysis comparing age-matched males and females ( = 4/group) was performed. Means were compared with Student's -test and variance of proportions with the Chi-squared test to a significance of < 0.05. There were small but significant differences including regional variation in villus height, which abolished when examining the small intestine as a whole. Sexually immature mice had increased CPI compared to mature animals. The most dramatic differences were seen in mice at weaning, which demonstrated shallower crypts, increased CPI, fewer Paneth and goblet cells, and more enterochromaffin cells. Examination of embryonic intestine revealed an underdeveloped mucosa lacking differentiated cells. There were minimal differences when comparing age-matched males and females. Small, but statistically significant differences in villus height, crypt depth, and crypt proliferation are present in mice across early developmental stages. Mice at weaning exhibit variation in crypt-villus cell composition compared to older animals, which may explain the propensity for certain intestinal conditions in the very young. Investigators studying the GI mucosa should employ consistent age-matching in order to allow direct comparison between studies.

中文翻译：

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C57BL/6J 小鼠小肠的粘膜特征因发育阶段而异


使用实验室小鼠的好处包括低成本、易于维护和分子工具的可访问性。然而，文献中实验小鼠的年龄差异很大。我们假设小鼠小肠在各个发育阶段都存在与年龄相关的变异。从不同年龄（E17 至 24 周；= 3-4/组）的 C57BL/6J 小鼠中收获小肠段。分析载玻片的形态参数、细胞类型和隐窝增殖指数（CPI）。对年龄匹配的男性和女性（= 4/组）进行了二次分析。平均值与学生检验进行比较，比例方差与卡方检验进行比较，显着性<0.05。存在微小但显着的差异，包括绒毛高度的区域差异，当检查整个小肠时，这种差异被消除。与成熟动物相比，性未成熟小鼠的 CPI 升高。最显着的差异出现在断奶时的小鼠中，其表现出隐窝变浅、CPI 增加、潘氏细胞和杯状细胞减少以及肠嗜铬细胞增加。对胚胎肠道的检查显示，粘膜发育不全，缺乏分化细胞。比较年龄匹配的男性和女性时，差异很小。在早期发育阶段的小鼠中，绒毛高度、隐窝深度和隐窝增殖存在微小但具有统计学意义的差异。与年老动物相比，断奶时的小鼠隐窝绒毛细胞组成有所不同，这可能解释了幼年小鼠出现某些肠道疾病的倾向。研究胃肠道粘膜的研究人员应采用一致的年龄匹配，以便在研究之间进行直接比较。