Spatiotemporal Characterisation of Key Cortical Developmental Markers in the Developing Ferret Brain.

Abstract

Introduction: The ferret is an important model for studying corticogenesis and cortical gyrification due to its small size, condensed cortical development timeline, and postnatal onset of gyrification. Its cortical progenitor and neuronal diversity closely resemble those of humans. However, detailed histological data across the rostrocaudal axis at critical embryonic and postnatal stages remain limited, particularly for recently identified progenitor subpopulations. This study aimed to comprehensively characterise the spatiotemporal expression of key progenitor and neuronal markers throughout the rostrocaudal axis of the developing ferret cortex at critical embryonic and postnatal ages. In doing so, the study sought to establish a foundational, descriptive atlas of neurodevelopmental marker expression across key time points and cortical regions and layers.

Methods: Immunofluorescent labelling of key neural progenitor and neuronal markers was performed on coronal ferret brain sections at embryonic (E34, E38) and postnatal (P2, P5, P15, P25) ages. Markers included PAX6, SOX2, TBR2, HOPX, CPLX3, CTIP2, SATB2, TUJ1, and DCX. Semi-quantitative analyses described the spatiotemporal distribution of each marker within defined cortical compartments along the rostrocaudal axis.

Results: Early radial glial markers PAX6 and SOX2 were abundant in the ventricular zone at embryonic stages, progressively declining postnatally as the subventricular zone (SVZ) expanded. Intermediate progenitor cells labelled by TBR2 showed high abundance in the SVZ prenatally, with a marked decrease after birth. HOPX identified outer radial glia populations exhibiting distinct temporal and spatial distributions, with increasing presence in the subplate (SP) and cortical plate during postnatal stages. CPLX3 expression emerged postnatally, delineating mature SP neurons with regionally patterned maturation. Deep- and superficial-layer neuronal markers CTIP2 and SATB2 displayed orderly laminar emergence, indicating progressive cortical layer formation. General neuronal markers TUJ1 and DCX highlighted the maturation and migration of post-mitotic neurons, with spatiotemporal gradients reflecting cortical differentiation across regions.

Conclusion: This detailed profiling fills critical gaps in the ferret histological record and serves as a valuable resource for investigations into mammalian corticogenesis using the ferret model. Through the integration of semi-quantitative assessments and qualitative analysis, this dataset contributes to the ongoing development of a detailed atlas of ferret brain development. These findings are expected to enhance the utility of the ferret model in neurodevelopmental research, particularly in translational contexts involving human cortical malformations.