Figure 9

A-C: Serotonergic innervation of the olfactory lobes. Double labeled sections showing glutamine synthetase-like immunoreactivity (GS; red) and serotonin immunoreactivity (5HT; green); confocal laser scan microscopy. A large population of serotonergic local interneurons in cell cluster (9) sends neurites into the core of the olfactory lobe (ON) by passing the median foramen (mF). This foramen is flanked by the non-columnar olfactory neuropils B and F the latter of which is connected by a neuropil bridge to neuropil E. The thick neurite bundles from cluster (9) interneurons, after entering the olfactory lobe, split into a large anterior (aB) and posterior bundle (pB). These bundles then branch out into finer bundles the fibers in which approach the proximal part of the olfactory glomeruli (arrows in C). Between the olfactory neuropil (ON) and the lateral antenna 1 neuropil (LAN), the soma of at least one large serotonergic neuron is located (arrowheads in B, C) but the axonal projection could not be traced. The dotted line in C encircles a blood vessel (BV).