English: Aplysia sensory-to-motor neuron co-cultures were treated with 5×5-HT (10 µM, 5 minutes) and RNA in situ hyrbridization was carried out using riboprobes. A: Confocal projection images showing cell bodies and neurites of sensory neurons and motor neurons. Tubulin protein immunostaining was used visualizing major axon and neurites. No antibody (anti-DIG antibody) and no probe were used as controls for in situ hybridization. B, C, D and E: Quantitation of imaging data. % change in fluorescence compared to back ground are shown in bar graphs. Data was normalized to mock treated controls. Error bars are SEM.