Media 5 - Dendritic bundles of ExU9 projecting to the lumbosacral intermediolateral column (IML)

Dendritic bundles of somatic motor neurons innervating the urethral rhabdosphincter (ExU9) project dorsally to the preganglionic neurons of the intermediolateral column (IML). Microinjection of the retrograde tracer cholera toxin subunit B (CTB) into the MPG of a male rat was taken up by sacral preganglionic neurons in the IML and somatic motor neurons of ExU9. CTB filled the entirety of the neuron, including the dendrites of motor neurons.

Visualization of motor neurons was achieved through whole tissue immunolabelling and clearing using a modified form of iDISCO for spinal cord. Motor neurons were immunolabelled via choline acetyltransferase (ChAT), while retrogradely-filled neurons were immunolabelled for CTB. Large volume imaging was performed on the light sheet microscope with a 12x lens (Ultramicroscope II, Miltenyi Biotec). Imaris (Bitplane) was used to view the dataset and create the media.