Dendritic spines of YFP mice longitudinally observed by two-photon microscopy.

<p>(A) Schematic of the imaging of the cortex using the two-photon carrier. (B) Locating the observation site by viewing vasculature under the thinned skull. (C) In vivo imaging the primary sensory cortex at 25× magnification, the dendritic spines and axons appear clearly. (D–G) Magnified images of (C) at (D) day 0 and (E) day 4, at (F) two weeks, and at (G) one month. Arrows: dendritic spines observed at the indicated four time points. Arrowheads: dendritic spines that disappeared on the fourth day. #: dendritic spines that were newly formed by the fourth day and remained at two weeks and one month. ☆: dendritic spines that were newly formed by the fourth day, but disappeared at two weeks. Scale bars: 0.5mm(B),10 μm (C), 2 μm (D, E, F, G).