Ferret brain possesses young interneuron collections equivalent to human postnatal migratory streams

Abstract

The human early postnatal brain contains late migratory streams of immature interneurons that are directed to cortex and other focal brain regions. However, such migration is not observed in rodent brain, and whether other small animal models capture this aspect of human brain development is unclear. Here, we investigated whether the gyrencephalic ferret cortex possesses human‐equivalent postnatal streams of doublecortin positive (DCX+) young neurons. We mapped DCX+ cells in the brains of ferrets at P20 (analogous to human term gestation), P40, P65, and P90. In addition to the rostral migratory stream, we identified three populations of young neurons with migratory morphology at P20 oriented toward: (a) prefrontal cortex, (b) dorsal posterior sigmoid gyrus, and (c) occipital lobe. These three neuronal collections were all present at P20 and became extinguished by P90 (equivalent to human postnatal age 2 years). DCX+ cells in such collections all expressed GAD67, identifying them as interneurons, and they variously expressed the subtype markers SP8 and secretagogin (SCGN). SCGN+ interneurons appeared in thick sections to be oriented from white matter toward multiple cortical regions, and persistent SCGN‐expressing cells were observed in cortex. These findings indicate that ferret is a suitable animal model to study the human‐relevant process of late postnatal cortical interneuron integration into multiple regions of cortex.

Dynamic Changes in the Neurogenic Potential in the Ventricular–Subventricular Zone of Common Marmoset during Postnatal Brain Development

“…4). Interestingly, arch-like organization is also observed in ferrets, which possess a gyrified cortex (Ellis JK et al 2019), suggesting that the presence of an arch is associated with cortical gyrification rather than evolutionary similarity with humans.…”

Multiple Origins of Secretagogin Expressing Cortical GABAergic Neuron Precursors in the Early Human Fetal Telencephalon

“…Furthermore, restructuring of the extracellular matrix by MMP2 promotes neuroblast migration (Hanics et al, 2017 ). Recent research has shown that in the early postnatal forebrain, nearby to the RMS, lies a dorsal migratory stream that supplies GABAergic neurons to late-developing prefrontal cortical areas in both humans (up to 5 months postnatally; Sanai et al, 2011 ; Paredes et al, 2016 ) and ferret (up to 90 days postnatally; Ellis et al, 2019 ). A large proportion of these interneurons express SCGN (Raju et al, 2018 ; Ellis et al, 2019 ).…”

Optical Tissue Clearing: Illuminating Brain Function and Dysfunction

“…Gasoni et al used an updated 3DISCO method to provide a quantitative analysis of gonadotropin-releasing hormone (GnRH) neuron origins, differentiation, migration, and their distribution 3D atlas in the fetal brain, revealing that GnRH positive neuron cells have potential roles in non-reproductive function (Figure 5 B) 90 . Additionally, the migration flow of immature neurons can also be studied in the early postnatal brain of some small animal models, which corresponds to the early development of human brains in this aspect (Figure 5 C) 91 , 92 . Furthermore, other biological stages that occur during neurodevelopment, including axonal guidance, synapse formation, and neuronal death, still need to be further studied through improved clearance techniques, leading to a comprehensive understanding of mammalian brain development.…”