Adult neurogenesis in a giant otter shrew (Potamogale velox)

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Brain and Mind Institute


Adult neurogenesis in mammals is typically observed in the subgranular zone of the hippocampal dentate gyrus and the subventricular zone. We investigated adult neurogenesis in the brain of a giant otter shrew (Potamogale velox), a semi-aquatic, central African rainforest mammal of the family Tenrecidae that belongs to the superorder Afrotheria. We examined neurogenesis immunohistochemically, using the endogenous marker doublecortin (DCX), which stains neuronal precursor cells and immature neurons. Our results revealed densely packed DCX-positive cells in the entire extent of the subventricular zone from where cells migrated along the rostral migratory stream to the olfactory bulb. In the olfactory bulb, DCX-expressing cells were primarily present in the granular cell layer with radially orientated dendrites and in the glomerular layer representing periglomerular cells. In the hippocampus, DCX-positive cells were identified in the subgranular and granular layers of the dentate gyrus and strongly labelled DCX-positive processes, presumably dendrites and axons of the newly generated granular cells, were observed in the CA3 regions. In addition, DCX immunoreactive cells were present in the olfactory tubercle, the piriform cortex and the endopiriform nucleus. While DCX-positive fibres have been previously observed in the anterior commissure of the hedgehog and mole, we were able to demonstrate the presence of DCX-positive cells presumably migrating across the anterior commissure. Taken together, the giant otter shrew reveals patterns of neurogenesis similar to that seen in other mammals; however, the appearance of possible neuronal precursor cells in the anterior commissure is a novel observation.


This work was published before the author joined Aga Khan University.

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