Kurrasch, DeborahMalik, Faizan2022-09-012022-09-012022-08Malik, F. (2022). Characterization of embryonic microglia in the developing hypothalamus of germ-free mice (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.http://hdl.handle.net/1880/115150https://dx.doi.org/10.11575/PRISM/40184Emerging evidence suggests that the maternal microbiome may influence the colonization, development, and function of microglia during embryonic brain development. Our objective was to conduct an unbiased and comprehensive morphometric evaluation of microglia morphology over several embryonic timepoints in the germ-free (GF) and specific pathogen free (SPF) tuberal hypothalamus. We hypothesized that hypothalamic microglia exhibit subtle differences in colonization, morphology, and/or dynamics in the embryonic brain of germ-free mice. This investigation was performed using two primary imaging modalities including histological, and acute organotypic slice time-series, imaging. Few morphological disturbances were observed between GF and SPF microglia across all embryonic timepoints analyzed. However, the changes we did observe, were robust and striking. GF microglia along the ventricular zone of the E14.5 tuberal hypothalamus exhibited several significant differences indicative of excess ramification. This finding was corroborated by the marked absence of an ameboid and highly phagocytic population of microglia in GF acute organotypic brain slices, otherwise present in the SPF condition. Furthermore, we observed a global decrease in CD68 expression among microglia in the tuberal hypothalamus. Interestingly, microglia in the parenchyma appeared unaffected by the absence of the microbiome. Together this data suggests that the maternal microbiome may discriminately influence discrete subpopulations of microglia in the tuberal hypothalamus at developmentally relevant time-points.engUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.braindevelopmentgut microbiomegerm-freemicrogliamorphometricsgerm-freefractal analysisembryonic brain developmentmicroglia morphologyNeurosciencemaster thesis