Cytoarchitecture of neurogenic niche and neuroblast clusters in the postnatal microminipig brain

The ventricular-subventricular zone (V-SVZ) is the largest neurogenic niche in the postnatal mammalian brain, but its organization and migratory dynamics remain poorly understood in gyrencephalic species. Here, we provide ultrastructural and three-dimensional characterization of the V-SVZ neuroblasts in postnatal microminipigs, the smallest pig strain with unique advantages for experimental neuroscience. Transmission electron microscopy revealed developmental changes in cell composition and cytoarchitecture, with migratory neuroblasts consistently associated with glial cells and vasculatures. Notably, serial block-face scanning electron microscopy revealed that tier 3 neuroblasts, a gyrencephalic-specific population, formed elongated, chain-like clusters aligned along vessels, with conserved intracellular features such as polarized organelle distributions and growth cone extension. Radial glial fibers were prominent in neonates but diminished with age, suggesting a developmental shift to vascular scaffolds as primary migration guides. These findings establish microminipigs as a tractable gyrencephalic model for studying postnatal neurogenesis, offering new opportunities for translational research on brain repair.