Early-life growth and cellular heterogeneity in the short-lived African turquoise killifish telencephalon.

The African turquoise killifish (Nothobranchius furzeri) is becoming a favorable model for neurobiological research. The combination of a short lifespan and a declining neuroregenerative capacity upon aging makes it ideally suited for research on brain aging and regeneration. A remarkable cellular diversity makes up the young-adult killifish telencephalon, characterized by highly proliferative non-glial progenitors and spatially distinct radial glia subtypes. In contrast to a relatively slow embryonic development, hatching is followed by a period of accelerated growth, in which the brain experiences a period of rapid expansion and maturation. In this study, we quantified the growth progression and maturation of the killifish telencephalon during early post-embryonic development. We discovered that, similar to in zebrafish, neuro-epithelial cells abut the neurogenic niches from early life onwards. Spatial data revealed qualitative and quantitative differences along the anterior-posterior axis and between pallial and subpallial regions in terms of growth pace. We confirmed generation of GABAergic neurons from the subpallial neurogenic niche and glutamatergic neurons from two pallial niches. Our data further showed a more widespread appearance of inhibitory neurons at hatching compared to in zebrafish.