title: The development of the corpus callosum in semilobar and lobar holoprosencephaly.
abstract: OBJECTIVE
  The objective of this study was to determine whether and how a true corpus callosum develops in milder cases of holoprosencephaly.
  
  
  METHODS
  The MR scans of seven patients with holoprosencephaly and a callosum-like structure were reviewed. The anatomy of the callosum-like structure and the pericallosal anatomy were evaluated.
  
  
  RESULTS
  Six of the seven cases had a posterior corpus callosum. The seventh case was indeterminate because lack of myelination prevented confirmation that the callosum-like structure consisted only of white matter. In each case the posterior corpus callosum formed posterior to white matter which spanned the interhemispheric fissure beneath a layer of cortical gray matter.
  
  
  CONCLUSIONS
  A posterior corpus callosum can develop in holoprosencephaly because the first callosal axons use the white matter of the undivided hemispheres as a bridge to cross the interhemispheric fissure.
authors.affiliation: Department of Radiology, University of Colorado Health Sciences Center, 4200 East Ninth Avenue, Campus Box A-034, Denver, CO 80262, USA.
authors.forename: D
authors.initials: D
authors.lastname: Rubinstein
authors.forename: A G
authors.initials: AG
authors.lastname: Cajade-Law
authors.forename: V
authors.initials: V
authors.lastname: Youngman
authors.forename: J M
authors.initials: JM
authors.lastname: Hise
authors.forename: M
authors.initials: M
authors.lastname: Baganz
mesh_terms: D061085:Agenesis of Corpus Callosum; D002675:Child, Preschool; D003337:Corpus Callosum / Q000473:pathology; D005260:Female; D016142:Holoprosencephaly / Q000175:diagnosis / Q000473:pathology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008279:Magnetic Resonance Imaging; D008297:Male