Development of a high resolution three-dimensional surgical atlas of the murine head for strains 129S1/SvImJ and C57Bl/6J using magnetic resonance imaging and micro-computed tomography.

The mouse has emerged as a major experimental model system for examining the functional properties of the mammalian CNS; both during development and following CNS injury. Histologic procedures currently used to determine the relative position of structures within the CNS are presently limited in their ability to take full advantage of this system for surgical and morphometric procedures. We present here the first three-dimensional interactive digital atlas of the murine brain and skull for two genetically important strains of mice; 129S1/SvImJ and C57Bl/6J. The final resolution of these digital atlases is 54 micro m(3). These representations of the murine brain and skull, in conjunction with our development of a new, more dynamic master coordinate system, provide improved accuracy with respect to targeting CNS structures during surgery compared with previous systems. The interactive three-dimensional nature of these atlases also provide users with stereotactic information necessary to perform accurate "off-axis" surgical procedures, as is commonly required for experiments such as in vivo micro-electroporation. In addition, three-dimensional analysis of the brain and skull shape in C57Bl, 129Sv, CD1, and additional murine strains, suggests that a stereotactic coordinate system based upon the lambda and rostral confluence of the sinuses at the sagittal midline, provides improved accuracy compared with the traditional lambda-bregma landmark system. These findings demonstrate the utility of developing highly accurate and robust three-dimensional representations of the murine brain and skull, in which experimental outputs can be directly compared using a unified coordinate system. The aim of these studies is to enhance comparative morphometric analyses and stereotactic surgical procedures in mice.