Longitudinal callosal fascicle

Longitudinal callosal fascicles (or Probst bundles) are abnormal collections of brain cells characteristic of patients with Agenesis of the corpus callosum. Failure of the neurons that normally make up the corpus callosum to cross the midline results in anomalous collection of these cells in both hemispheres. Longitudinal callosal fascicles were originally described by Moriz Probst in 1901 by gross anatomical observation. More recently, these anomalies are detected by Magnetic Resonance Imaging or Diffusion Tensor Imaging.