Neurogenesis in a marsupial: the brush-tailed possum (Trichosurus vulpecula). I. Visual and auditory pathways

The times of origin of neurons in the visual and auditory systems were studied in a marsupial, the brush-tailed possum, using tritiated thymidine autoradiography. Within the subcortical visual pathways, most neurons are generated between postnatal days 5 and 21, and the neurons of the primary visual cortex up to postnatal day 68. In the subcortical auditory pathways, most neurons are generated between postnatal days 5 and 28, and all auditory cortex neurons have appeared by postnatal day 46. Neurons in a single layer of cerebral cortex are generated during a period of about 2 weeks. Thus cortical neurogenesis in marsupials extends over a period similar to that seen in primates.