title: Septo-temporal distribution and lineage progression of hippocampal neurogenesis in a primate (Callithrix jacchus) in comparison to mice.
abstract: Adult born neurons in the hippocampus show species-specific differences in their numbers, the pace of their maturation and their spatial distribution. Here, we present quantitative data on adult hippocampal neurogenesis in a New World primate, the common marmoset (Callithrix jacchus) that demonstrate parts of the lineage progression and age-related changes. Proliferation was largely (∼70%) restricted to stem cells or early progenitor cells, whilst the remainder of the cycling pool could be assigned almost exclusively to Tbr2+ intermediate precursor cells in both neonate and adult animals (20-122 months). Proliferating DCX+ neuroblasts were virtually absent in adults, although rare MCM2+/DCX+ co-expression revealed a small, persisting proliferative potential. Co-expression of DCX with calretinin was very limited in marmosets, suggesting that these markers label distinct maturational stages. In adult marmosets, numbers of MCM2+, Ki67+, and significantly Tbr2+, DCX+, and CR+ cells declined with age. The distributions of granule cells, proliferating cells and DCX+ young neurons along the hippocampal longitudinal axis were equal in marmosets and mice. In both species, a gradient along the hippocampal septo-temporal axis was apparent for DCX+ and resident granule cells. Both cell numbers are higher septally than temporally, whilst proliferating cells were evenly distributed along this axis. Relative to resident granule cells, however, the ratio of proliferating cells and DCX+ neurons remained constant in the septal, middle, and temporal hippocampus. In marmosets, the extended phase of the maturation of young neurons that characterizes primate hippocampal neurogenesis was due to the extension in a large CR+/DCX- cell population. This clear dissociation between DCX+ and CR+ young neurons has not been reported for other species and may therefore represent a key primate-specific feature of adult hippocampal neurogenesis.
authors.affiliation: Functional Neuroanatomy, Institute of Anatomy, University of Zürich Zürich, Switzerland ; Neuroscience Center Zurich, University of Zürich and ETH Zürich Zürich, Switzerland.
authors.forename: Irmgard
authors.initials: I
authors.lastname: Amrein
authors.affiliation: Functional Neuroanatomy, Institute of Anatomy, University of Zürich Zürich, Switzerland.
authors.forename: Michael
authors.initials: M
authors.lastname: Nosswitz
authors.affiliation: Functional Neuroanatomy, Institute of Anatomy, University of Zürich Zürich, Switzerland.
authors.forename: Lutz
authors.initials: L
authors.lastname: Slomianka
authors.affiliation: Functional Neuroanatomy, Institute of Anatomy, University of Zürich Zürich, Switzerland ; Institute of Human Movement Sciences and Sport, Department of Health Sciences and Technology, ETH Zürich Zürich, Switzerland.
authors.forename: R Maarten
authors.initials: RM
authors.lastname: van Dijk
authors.affiliation: Functional Neuroanatomy, Institute of Anatomy, University of Zürich Zürich, Switzerland.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Engler
authors.affiliation: Functional Neuroanatomy, Institute of Anatomy, University of Zürich Zürich, Switzerland.
authors.forename: Fabienne
authors.initials: F
authors.lastname: Klaus
authors.affiliation: Inserm U846, Stem Cell and Brain Research Institute, Bron France ; Université de Lyon, Bron France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Raineteau
authors.affiliation: Neuroscience Center Zurich, University of Zürich and ETH Zürich Zürich, Switzerland.
authors.forename: Kasum
authors.initials: K
authors.lastname: Azim
keywords: Callithrix jacchus; comparative; hippocampus; marmoset; neurogenesis; septo-temporal; transcription factors