The lizard cerebral cortex as a model to study neuronal regeneration
The medial cerebral cortex of lizards, an area homologous to the hippocampal fascia dentata, shows delayed postnatal neurogenesis, i.e., cells in the medial cortex ependyma proliferate and give rise to immature neurons, which migrate to the cell layer. There, recruited neurons differentiate and give rise to zinc containing axons directed to the rest of cortical areas, thus resulting in a continuous growth of the medial cortex and its zinc-enriched axonal projection. This happens along the lizard life span, even in adult lizards, thus allowing one of their most important characteristics: neuronal regeneration. Experiments in our laboratory have shown that chemical lesion of the medial cortex…
Retrograde transport of sodium selenite and intracellular injection of micro-ruby: a combined method to describe the morphology of zinc-rich neurones.
Abstract Zinc is found in synaptic vesicles in a large number of glutamatergic systems. Its involvement in neurotransmission and neurological disorders has been suggested. There are methods for tracing these circuits, but they do not fill the dendritic tree. In this study, extracellular selenite injections in vivo were combined with intracellular injection of fluorochromes in fixed tissue to reveal the morphology of these zinc-rich neurones. Intraperitoneal and intracerebral injections of sodium selenite alone or intracerebral injections of selenite combined with bisbenzimide were made in the visual cortex of the rat in order to locate the somata of zinc-rich neurones. After 24 h of retrogr…
Neurons of the dentate molecular layer in the rabbit hippocampus.
The molecular layer of the dentate gyrus appears as the main entrance gate for information into the hippocampus, i.e., where the perforant path axons from the entorhinal cortex synapse onto the spines and dendrites of granule cells. A few dispersed neuronal somata appear intermingled in between and probably control the flow of information in this area. In rabbits, the number of neurons in the molecular layer increases in the first week of postnatal life and then stabilizes to appear permanent and heterogeneous over the individuals' life span, including old animals. By means of Golgi impregnations, NADPH histochemistry, immunocytochemical stainings and intracellular labelings (lucifer yellow…
Improved technique for stereotactic placement of nerve grafts between two locations inside the rat brain
Peripheral nerve grafts have shown the ability to facilitate central axonal growth and regenerate the adult central nervous system. However, the detailed description of a technique for atraumatic graft placement within the brain is lacking. We present a stereotactic procedure to implant a peripheral nerve graft within a rat's brain with minimal brain tissue damage. The procedure permits a correct graft placement joining two chosen points, and the survival and integration of the graft in the host tissue with a light glial reaction, with evidence of central axonal growth inside the graft, at least up to 8 weeks after its implantation. (C) 2008 Elsevier B.V. All rights reserved.