protocerebral bridge [FBbt_00003668]

protocerebral bridge

ID: FBbt_00003668

A handle bar-shaped synaptic neuropil located just posterior to the fan-shaped body. Its lateral edge ends at the posterior end of the inferior clamp (ICL) near the medial equatorial fascicle (MEF). A row of 18 connected slices (9 on each side of the midline, numbered 1-9 from medial to lateral) that forms a dorso-posteriorly located part of the central complex embedded in the cortex between the calyces of the two mushroom bodies.

The identification of the most medial slice (slice 1) by Wolff et al. (2015) meant that the domain that was previously called slice 1 corresponds in fact to slice 2. Each of the two neighboring slices (2-3, 4-5, 6-7, 8-9) are associated more closely because small-field columnar neurons innervate the fan-shaped body via the protocerebral bridge, and these neurons are generated by the same neuroblasts, forming four groups on each side of the midline, from lateral to medial: segment pair W, X, Y and Z (Boyan and Williams et al., 2011; Ito and Awasaki, 2008).