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Fig. 5 | BMC Biology

Fig. 5

From: Effects of sleep and wake on astrocytes: clues from molecular and ultrastructural studies

Fig. 5

Astrocytic coverage of cortical synapses increases after CSR. ad Examples of electron microscope images showing PAP (a) and PAP+ (c) spines, with their relative 3D reconstructions (b, d). In (a) and (c), PAPs are depicted in light blue and spine heads (S) are in yellow. B = presynaptic bouton; A = axon; D = dendrite. The ASI is traced in red and the apposed astrocytic surface on the spine head is in green. Scale bar = 250 nm. In (d), the PAP embracing the spine (*) has been made transparent to allow a view of the spine head underneath. Note that the apposed astrocytic surface (green) contacts the ASI (red) on one side. e Percentage of PAP and PAP+ spines per dendrite in layer II cortical fields for S (n = 9 dendrites; PAP, 17.95 ± 6.54 %; PAP+, 82.05 ± 6.53 %), SD (n = 9 dendrites; PAP, 19.16 ± 5.18 %; PAP+, 80.84 ± 5.18 %) and CSR (n = 8 dendrites; PAP, 18.37 ± 7.07 %, PAP+, 81.62 ± 7.07 %). PAP, Kruskal–Wallis, P = 0.96; PAP+, Kruskal–Wallis, P = 0.96. f Correlation between area of the apposed astrocytic surface and spine head volume in S (n = 250, green, r = 0.61, P < 0.0001), SD (n = 300, red, r = 0.6, P < 0.0001) and CSR (n = 254, brown, r = 0.69, P < 0.0001). g Apposed astrocytic surface area in S (n = 250, 0.15 ± 0.17 μm2), SD (n = 300, 0.16 ± 0.17 μm2) and CSR (n = 254, 0.23 ± 0.29 μm2). SD vs CSR, Mann-Whitney (MW), *P < 0.0001; S vs CSR, MW, *P < 0.0001. h Apposed astrocytic surface area to spine head surface area ratio in S (n = 250, 10.77 ± 8.59 %), SD (n = 300, 10.65 ± 8.38 %) and CSR (n = 254, 13.89 ± 9.84 %). SD vs CSR, MW, *P = 0.003, S vs CSR, MW, *P = 0.0005. i Apposed astrocytic surface area to spine head surface area ratio for spines with small (head volume between 0th and 50th percentiles), medium (50th to 75th percentiles) and large (>75th percentile) spine head volume in S (green), SD (red) and CSR (brown). Note that CSR showed higher ratios than S and SD for medium (MW; SD vs CSR, *P = 0.03; S vs CSR, *P = 0.027) and large spines (MW; SD vs CSR, *P = 0.0003; S vs CSR, *P = 0.0002). j Example of spine head including the spine apparatus (*). PAP indicates the astrocytic process, S the spine head and B the presynaptic bouton. Scale bar = 300 nm. k Apposed astrocytic surface area to spine head surface area ratio for spines with and without the spine apparatus in S (green), SD (red) and CSR (brown). Note that CSR showed higher ratios than S and SD for spines with spine apparatus (MW; SD vs CSR, *P = 0.03; S vs CSR, *P = 0.0003). All values are mean ± standard deviation

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