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Microglial cells are responsible for inflammatory and immune responses in many living organisms. These cells originate from macrophages, which are resident cells of the central nervous system (CNS). Although microglial cells are considered to be “resting” or “active”, it has been determined that they are constantly surveying their environment in search of injury or invaders (i.e. pathogens). Amphibians are primary subjects for this research because they possess microglia that allow regeneration of their central nervous system, particularly their tail. Although amphibians possess this quality, and urodeles, such as axolotls or other salamanders, are able to regenerate throughout their whole lives, anurans such as frogs and toads are only capable of this regeneration during their larval stages. I hope that by mapping out and describing the morphology of microglia among embryonic and larval amphibians I may come to understand more about regeneration capabilities among amphibians, as well as the role(s) that microglia may play in overall development. I have sacrificed both Ambystoma mexicanum (axolotl) and Xenopus laevis embryos and larvae in an attempt to answer this question. The Abystoma embryos and larvae were embedded in paraffin, cryo-gel, and plastic, while the Xenopus were embedded only in paraffin. The tissue was sectioned and put onto slides, then various staining procedures were completed. Hematoxylin and eosin (H&E) staining was used to better observe the anatomy and general cellular morphology of the specimens, whereas tomato lectin (TL) was used to specifically target macrophages and microglia, as well as their processes. Through the observation of the collected data, I was able to determine that microglial cells are in fact present in the CNS of Ambystoma and Xenopus, however further research must be completed to conclude the exact roles microglia have in the development of these specimens.
Weggeman, Sarah, "Distribution of Microglia in the Central Nervous System of Embryonic and Larval Amphibians" (2015). Biology Summer Fellows. 5.