Figure 2.

Prolonged cooling of mature brain slices leads to the disappearance of dendritic spines. A, Dendritic spines (arrowheads) in mature organotypic cultures at physiological temperatures remain present throughout continuous recordings up to 8 hr. Two images show a dendrite in a control culture maintained at 37°C at time 0 and 8 hr later (8.45). Scale bar, 3 μm. B, Several dendrites (arrowheads) in a mature slice culture that had been incubated overnight at 24°C lack the presence of the majority of spines on its surface. Scale bar, 5 μm. C, Acutely cut slices from the brains of adult mice were kept overnight at 4°C, fixed, and single neurons were labeled with a lipophilic dye (DiI). The asterisk indicates the approximate site of DiI entry in the slice. Dendrites lost their spines after the prolonged cooling to 4C° (arrowheads). Scale bar, 5 μm.