Fig. 4. Three-dimensional analysis of terminals of FS (A–C) and LTS (D–F) cells. InB1, C1, C2, D1, D2
, and E1
, two images are shown for stereoscopic observation. A1, 3-D reconstruction images of a terminal of FS cell number 1 and associated structures are rotated ∼25° each from left to right. An intracellularly labeled axon terminal of the FS cell (red) makes a symmetrical synapse on a postsynaptic spiny dendrite (green). Two of the spine heads receive asymmetrical synapses (blue and dark blue). The other terminal (pink) makes a symmetrical contact on the other side of the dendrite. A2, The same dendrite as in A1
is rotated in the same way except that synaptic junctions are indicated by the same colors as the terminal boutons in A1
. The synaptic junctional area of the FS cell terminal (red) was 0.298 μm2. B1, Two successive axonal boutons of FS cell number 1 make synaptic junctions 0.8 μm apart on the same proximal dendrite 2 μm distant from the soma. Two synaptic junctions are shown inB2
at the same magnification as inA. The synaptic junctional areas of the FS cell terminals were 0.19 (left) and 0.18 μm2(right), respectively.C1, Another axon terminal (red) of FS cell number 1 makes a symmetrical synaptic contact on a spine neck. The spine receives an asymmetrical terminal on the head (dark blue) and another spine also an asymmetrical terminal (blue). Another terminal (orange) makes a symmetrical synapse on the dendritic shaft.C2, The same dendrite as inC1
except that synaptic junctions are indicated by the same colors as the terminal boutons inC1
. The synaptic junctional area of the FS cell terminal (red) was 0.04 μm2.D1, A terminal of LTS cell number 1 (red) makes a symmetrical synaptic contact on a shaft of a spiny dendrite (green).D2, The synaptic junctional area (0.088 μm2) is indicated by red. E1, A terminal of LTS cell number 2 (red) makes a symmetrical synaptic junction on a trunk of a spiny dendrite (green). Two spines nearby receive asymmetrical synaptic terminals on the head (blue).E2, The synaptic junctional area (0.068 μm2) is indicated by red. F1, A terminal of LTS cell number 1 and associated structures are rotated ∼30° from left to right. The terminal (red) makes a symmetrical synaptic contact on a spine stalk. The spine head receives an asymmetrical terminal (dark blue) and other three spines, also asymmetrical terminals (blue), on the head.F2, The same dendrite as inF1
is rotated in the same way, except that synaptic junctions are indicated by the same colors as the terminal boutons in F1
. The synaptic junctional area of the terminal (red) was 0.068 μm2. Scale bars: A,B2, C–F, 0.5 μm;B1
, 0.8 μm.