Fabrication of an Expandable Brain Matrix Customizable Across Developmental Stages

Increasing interest in using newborn piglets as a study model for neonatal development and pathology has raised the need for a brain matrix to accurately acquire histological sections. However, the fast growth of the newborn brain limits the utility of commercially available matrices to a narrow developmental window. Therefore, an adjustable brain matrix construction method was developed. First, a glass container was placed on wet ice, and a layer of 4% agarose gel was laid at the bottom. Next, a formalin-fixed brain was placed on this layer and embedded with 4% agarose gel. After the gel solidified, the gel above the brain was carefully removed, and the brain was extracted. The cavity was filled with 4% agarose gel with 2% Indian Ink. After solidification, the gel block was removed and sliced into the desired thickness (2 mm or 5 mm) and orientation (coronal or sagittal) to print the brain templates on scale paper. The templates were copied to a series of transparent acrylic plates (2 mm or 5 mm thickness) and cut out accordingly on a band saw. Finally, the plates were assembled and secured with three sets of bolts and nuts through predrilled alignment holes to build a customized brain matrix. Construction of both coronal and sagittal matrices is illustrated for a neonatal day 5 piglet brain with steps of 2 mm and a coronal matrix for postnatal day 32-38 brains with steps of 5 mm. By adding or removing proper acrylic plates, the matrix was adjusted to adapt to the various sizes of piglet brains. Thus, a simple, cost-effective method to customize brain matrices for varied sizes of large animals is introduced to the neurological research community.