Figure 9

Dynamics of glutamate expression and glial cell processes in the maturing mushroom body α/β lobe. The α/β lobe is the last born domain of the MB, formed during pupation. This lobe is entirely covered by glial cell processes that express Glu signaling molecules (dEAAT1, GS). The cell bodies of these glial cells reside outside the MBs. The α/βc consists of: newborn KCs (magenta bright: Glu+++), youngest KCs (pale magenta: Glu+), and mature α/βc KCs (green: Glu-). (A) At the moment of eclosion and the first hour thereafter, newborn axons from the α/βc are strongly Glu-positive (Glu+++, magenta bright). These grow down through the surrounding, and older, α/βc neurons: older processes are shown green displaced by the youngest α/βc axons (pale magenta). After eclosion, the only volume of the α/β lobe that does not have glial processes is that in which occur newborn axons of Glu-containing α/βc neurons (bright magenta). (B) Twenty-four hours after eclosion, Glu expression in the core neurons has a lower intensity (pale magenta: Glu+) and at the same time delicate extensions of glial cells are seen penetrating into the α/βc. (C) Ten days after eclosion: glial cells provide a mesh like network inside the α/β lobes and Glu immunoreactivity is no longer detectable in the core neurons. ped, pedunculus.