title: GAP-43 Immunoreactivity in the brain of the developing and adult wallaby ( Macropus eugenii).
abstract: We have examined the distribution of immunoreactivity for GAP-43 in the developing and adult brain of a diprotodontid metatherian, the tammar wallaby ( Macropus eugenii). The distribution of GAP-43 immunoreactivity in the neonatal wallaby brain was strikingly heterogeneous, in contrast to that reported for the newborn polyprotodontid opossum. Immunoreactivity for GAP-43 in the developing wallaby brain showed a caudal-to-rostral spatiotemporal gradient, with the brainstem well in advance of the telencephalon throughout the first 100 days of postnatal life. In many regions examined, GAP-43 immunoreactivity passed through the following phases: 1. intense immunoreactivity in developing fiber tracts and occasional somata; 2. diffuse homogeneous immunoreactivity; 3. selective loss of immunoreactivity in particular nuclei or cortical regions. In the isocortex, selective loss of GAP-43 immunoreactivity in the somatosensory and visual cortex (at postnatal day 115) coincided with the maturation of the laminar distribution of terminal thalamocortical axonal fields. Within adult cortical regions, GAP-43 immunoreactivity was highest in layer I of all regions, lower layers (V and VI) of primary somatosensory and visual cortices, layers II/III of motor and cingulate cortex, and layer IV of entorhinal cortex. Our findings suggest that, while patterning of GAP-43 immunoreactivity in the mature brain is similar across meta- and eutheria, there may be early developmental differences in the distribution of GAP-43 immunoreactivity between poly- and diprotodontid metatheria.
authors.affiliation: Department of Anatomy, The University of NSW, 2052 Sydney, NSW, Australia.
authors.forename: Maria
authors.initials: M
authors.lastname: Hassiotis
authors.forename: Ken W S
authors.initials: KW
authors.lastname: Ashwell
authors.forename: Lauren R
authors.initials: LR
authors.lastname: Marotte
authors.forename: Sabine
authors.initials: S
authors.lastname: Lensing-Höhn
authors.forename: Jürgen K
authors.initials: JK
authors.lastname: Mai
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001921:Brain / Q000254:growth & development / Q000378:metabolism*; D019922:GAP-43 Protein / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D007614:Macropodidae / Q000502:physiology*; D009830:Olfactory Bulb / Q000254:growth & development / Q000378:metabolism; D009893:Opossums / Q000502:physiology; D051381:Rats; D013045:Species Specificity
chemical_list: D019922:GAP-43 Protein