ABSTRACT
Autism spectrum disorders are characterized by impaired social and communication skills and seem to result from altered neural development. We sought to determine whether the anatomy of the meninges and extracellular matrix (ECM) is altered in an animal model of autism, the BTBR T+ tf/J mouse. This mouse displays white matter tract anatomical defects and exhibits several symptoms of autism. Immunofluorescence cytochemistry for laminin, a major ECM marker, was performed on series of coronal sections of the adult BTBR T+ tf/J brain and the anatomy was analyzed in comparison to B6 wild type mice. Laminin immunoreactivity visualized meninges, blood vessels and the subventricular zone (SVZ) stem cell-associated ECM structures, which I have named fractones. All BTBR T+ tf/J mice observed showed the same forebrain defects. The lateral ventricle volume was severely reduced, the falx cerebri elongated, the arteries enlarged and the choroid plexus atrophied. Compared to B6 mice, fractone numbers in BTBR T+ tf/J mice were reduced by a factor three in the SVZ of the anterior portion of the lateral ventricle. This represents the primary neurogenic zone during adulthood. Fractones were reduced by a factor 1.5 in posterior portions of the lateral ventricle. Moreover, fractone size was reduced throughout the lateral ventricle SVZ. These results show hitherto unsuspected alterations in connective tissue/vasculature and associated ECM in the adult BTBR T+ tf/J mouse. The drastic changes of the connective tissue and ECM in the neurogenic zone of the lateral ventricle may contribute to incorrect neurogenesis during developmental and adult stages.
