(A1, A2 upper panels) Globuli cell domains reconstructed from serial sections from Neogonodactylus oerstedii (A1) and Periplaneta americana (A2). (A1, A2 middle panels): Globuli cell packing (reduced-silver-stained sections). (A1, A2 lower panels) Golgi impregnations showing corresponding neuronal organization in calyces. (B) Three-dimensional reconstruction from serial sections of N. oerstedii, stained by reduced silver, demonstrates a mushroom body consisting of a globuli cell layer (gc, green), a calyx (Ca, cyan) and four distinct columns (Clm 1–4, purple, magenta, blue, orange), with Clm 1 accompanied by distal branch (Clm 1*). (C) Golgi impregnation of the columns, each defined by its characteristic arrangement of parallel fibers. (D) Clawed specializations (arrowed) are mushroom body identifiers found on dendrites arising distally from parallel fibers. These are shown here in the stomatopod (upper panel), cockroach (middle panel) and honeybee (lower panel). (E, F) The dense spiny processes of efferent (output) neurons form discrete domains along the length of the columns. Paired corresponding arrangements are here demonstrated from the stomatopod N. oerstedii (left in each pair) and P. americana. Scale bars: A, panels, second row, 25 µm; lower panels, 20 µm; C, 100 µm; D, scales in all panels, 10 µm; E-F, all scales = 50 µm.