start stage end stage brainstem and spinal white matter medial longitudinal fasciculus zebrafish_anatomy The medial longitudinal fasciculus (MLF) is a pair of crossed fiber tracts (group of axons), that begin with in the nucleus of the MLF and run ventral to the rhombencephalic ventricle, towards the caudal end of the medulla oblongata. The dorsal portion of the MLF including the Mauthner axon continues into the spinal chord while the ventral portion of the MLF associates with other fiber systems in the funiculus ventralis prior to reaching the spinal chord. Throughout the most of its rhombencephalic extent the MLF is intersected by the ventral rhombencephalic commissure. TAO:0000543 ZFA:0000543 MLF unknown adult