Media 6 - Intersegmental axonal projections of sacral somatic motor neurons

A subset of axons of sacral somatic motor neurons that innervate the tail and levator ani (Tail9) possess intersegmental projections. These axons initially project laterally in the transverse plane before turning at a right angle and continuing within the ventrolateral white matter tracts to the next segment, either L6 or S2.

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). Large volume imaging was performed on the light sheet microscope with a 12x lens (Ultramicroscope II, Miltenyi Biotec). Neurons and axons were traced using Neurolucida 360's (MBF Bioscience) User Guided tree tracing function, with Directional Kernels the tracing algorithm of choice.