Cocultures

The physiology of long-range neural pathways in the brain is not amenable to study under well-controlled in vitro

FIGURE 2 Fluorescence imaging in hippocampal slice cultures. A: Low-power charge-coupled device (CCD) video image of two CA1 cells biolistically transfected with DNA for green fluorescent protein in a hippocampal slice culture prepared using the roller tube method. Higher-power CCD images of dendritic spines along apical dendritic segments are shown below. Scale bars: 50mm upper image, 2mm lower images. B: CCD images of an axonal growth cone of a sprouting CA3 cell axon 5 days after Schaffer collateral transection. The pair of images was captured 15 minutes apart and illustrate the dynamic processes occurring at the growth cone during axonal growth. Scale bars: 1 mm. C: CCD images of an apical terminal dendrite injected intracellularly with a red fluorescent dye (Alexa 568)(left) and an image of the fluorescence emission of the Ca2+-sensitive dye fluo-4 in the same dendrite as the result of a glutamate-induced dendritic plateau potential (see Cai et al., 2004). Scale bars: 2 mm. These results illustrate the excellent optical properties of hippocampal slice cultures prepared with the roller-tube method.

FIGURE 2 Fluorescence imaging in hippocampal slice cultures. A: Low-power charge-coupled device (CCD) video image of two CA1 cells biolistically transfected with DNA for green fluorescent protein in a hippocampal slice culture prepared using the roller tube method. Higher-power CCD images of dendritic spines along apical dendritic segments are shown below. Scale bars: 50mm upper image, 2mm lower images. B: CCD images of an axonal growth cone of a sprouting CA3 cell axon 5 days after Schaffer collateral transection. The pair of images was captured 15 minutes apart and illustrate the dynamic processes occurring at the growth cone during axonal growth. Scale bars: 1 mm. C: CCD images of an apical terminal dendrite injected intracellularly with a red fluorescent dye (Alexa 568)(left) and an image of the fluorescence emission of the Ca2+-sensitive dye fluo-4 in the same dendrite as the result of a glutamate-induced dendritic plateau potential (see Cai et al., 2004). Scale bars: 2 mm. These results illustrate the excellent optical properties of hippocampal slice cultures prepared with the roller-tube method.

conditions because it is difficult or impossible to maintain these contacts during the preparation of ex vivo slices. In slice cultures, however, slices from two brain regions that are normally connected in vivo can be cocultured adjacent to one another, and they will form connections in vitro. This approach has been taken for septo-hippocampal (Gähwiler and Brown, 1985), thalamocortical (Molnar and Blakemore, 1991), corticostriatal (Ostergaard et al., 1991), entorhinal cortex-hippocampal (Li et al., 1994), and locus coeruleus-hippocampal connections (Knöpfel et al., 1989). Some specificity is also maintained in the growth of these fiber pathways, as illustrated by the observation that cholinergic fibers from medial septal cells will not grow into cerebellar tissue slices, just as they do not normally innervate the cerebellum in vivo unless they are "tricked" by the addition of nerve growth factor (Gahwiler and Hefti, 1987; Gahwiler et al., 1991).

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