part of brain development mushroom body development The process whose specific outcome is the progression of the mushroom body over time, from its formation to the mature structure. The mushroom body is composed of the prominent neuropil structures of the insect central brain, thought to be crucial for olfactory associated learning. These consist mainly of a bulbous calyx and tightly packaged arrays of thin parallel fibers of the Kenyon cells. GO:0016319 biological_process anatomical structure development