The ankyrinB gene encodes 150, 220, and 440 kDa ankyrinB, which are membrane-associated structural proteins expressed in brain and heart. Biochemical functions of ankyrinB include linkage of members of the L1 family of cell adhesion molecules to spectrin-actin complexes. Physiological functions of ankyrins in brain are not known. We have disrupted the gene encoding ankyrinB in mice, with the consequence that these animals die within 20 days of birth. Brains of mutant animals reveal loss of major nerve tracts and enlarged ventricles, based on histology. We wish to evaluate the three-dimensional structure of the brains of normal and mutant neonatal mice by MR microscopy to better appreciate macroscopic consequences of ankyrinB deficiency, and in particular the details of ventricular enlargement. Animals well be sacrificed and the tissues placed in 4% buffered formaldehyde.