Model of potential mechanism(s) of early prenatal dietary sodium restriction on microglia numbers and postnatal failure to prune gustatory terminals in the NST. A maternal low-sodium diet impacts the environment of the embryo when microglia progenitors are transported into the emerging brain of the embryo (∼E8.5) by altering the cellular processes of the progenitors and/or compromising the number of progenitors that take up residence in the NST (solid arrow). This produces a decrease in microglia numbers. A later consequence (∼3–4 wk) of this altered early environment is decreased numbers of microglia and a failure to prune gustatory terminal fields in the NST (solid arrow). The dotted arrow denotes a direct link between the early and later effects, which could involve multiple molecular mechanisms for pruning and maintenance of terminal field integrity in adulthood (e.g., IL-34 and IL-33).