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Analysis of shape and spatial interaction of synaptic vesicles using data from focused ion beam scanning electron microscopy (FIB-SEM).

Khanmohammadi M, Waagepetersen RP, Sporring J - Front Neuroanat (2015)

Bottom Line: Statistics for marked point processes were employed to study spatial interactions between vesicles.We found that the synaptic vesicles in excitatory synapses appeared to be of oblate ellipsoid shape and in inhibitory synapses appeared to be of cigar ellipsoid shape, and followed a systematic pattern regarding their orientation toward the active zone.Moreover, there was strong evidence of spatial alignment in the orientations of pairs of synaptic vesicles, and of repulsion between them only in excitatory synapses, beyond that caused by their physical extent.

View Article: PubMed Central - PubMed

Affiliation: Computer Science Department, University of Copenhagen Copenhagen, Denmark.

ABSTRACT
The spatial interactions of synaptic vesicles in synapses were assessed after a detailed characterization of size, shape, and orientation of the synaptic vesicles. We hypothesized that shape and orientation of the synaptic vesicles are influenced by their movement toward the active zone causing deviations from spherical shape and systematic trends in their orientation. We studied three-dimensional representations of synapses obtained by manual annotation of focused ion beam scanning electron microscopy (FIB-SEM) images of male mouse brain. The configurations of synaptic vesicles were regarded as marked point patterns, where the points are the centers of the vesicles, and the mark of a vesicle is given by its size, shape, and orientation characteristics. Statistics for marked point processes were employed to study spatial interactions between vesicles. We found that the synaptic vesicles in excitatory synapses appeared to be of oblate ellipsoid shape and in inhibitory synapses appeared to be of cigar ellipsoid shape, and followed a systematic pattern regarding their orientation toward the active zone. Moreover, there was strong evidence of spatial alignment in the orientations of pairs of synaptic vesicles, and of repulsion between them only in excitatory synapses, beyond that caused by their physical extent.

No MeSH data available.


Related in: MedlinePlus

Histograms of univariate shape characteristics of all the synaptic vesicles included in this study. (A) Aspect ratio(a/c) in average over five asymmetric synapses. (B) Aspect ratio(b/c) in average over five asymmetric synapses. (C) Aspect ratio(a/b) in average over five asymmetric synapses. (D) Aspect ratio(a/c) in a symmetric synapse. (E) Aspect ratio(b/c) in a symmetric synapse. (F) Aspect ratio(a/b) in a symmetric synapse.
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Figure 4: Histograms of univariate shape characteristics of all the synaptic vesicles included in this study. (A) Aspect ratio(a/c) in average over five asymmetric synapses. (B) Aspect ratio(b/c) in average over five asymmetric synapses. (C) Aspect ratio(a/b) in average over five asymmetric synapses. (D) Aspect ratio(a/c) in a symmetric synapse. (E) Aspect ratio(b/c) in a symmetric synapse. (F) Aspect ratio(a/b) in a symmetric synapse.

Mentions: Results were obtained both for vesicles in each synapse separately and for all around 500 vesicles pooled together for asymmetric synapses. The second column in Table 1 shows that the mean surface areas of the synaptic vesicles are similar in all synapses. The histograms of shape characteristics in Figure 4 further show that the vesicles are far from spherical. Table 1 shows that the mean a/b ratio and mean b/c ratio appear to be considerably smaller than the mean a/c ratio for all asymmetric synapses. This also holds for the mean ratios for all vesicles considered jointly. These findings indicate that vesicles are of oblate ellipsoidal shape in the asymmetric synapses. On the other hand, in symmetric synapses the mean a/b ratio and mean b/c ratio appear to be very similar and considerably smaller than the mean a/c ratio. This indicates that the synaptic vesicles are of cigar ellipsoidal shape in the symmetric synapse.


Analysis of shape and spatial interaction of synaptic vesicles using data from focused ion beam scanning electron microscopy (FIB-SEM).

Khanmohammadi M, Waagepetersen RP, Sporring J - Front Neuroanat (2015)

Histograms of univariate shape characteristics of all the synaptic vesicles included in this study. (A) Aspect ratio(a/c) in average over five asymmetric synapses. (B) Aspect ratio(b/c) in average over five asymmetric synapses. (C) Aspect ratio(a/b) in average over five asymmetric synapses. (D) Aspect ratio(a/c) in a symmetric synapse. (E) Aspect ratio(b/c) in a symmetric synapse. (F) Aspect ratio(a/b) in a symmetric synapse.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4555025&req=5

Figure 4: Histograms of univariate shape characteristics of all the synaptic vesicles included in this study. (A) Aspect ratio(a/c) in average over five asymmetric synapses. (B) Aspect ratio(b/c) in average over five asymmetric synapses. (C) Aspect ratio(a/b) in average over five asymmetric synapses. (D) Aspect ratio(a/c) in a symmetric synapse. (E) Aspect ratio(b/c) in a symmetric synapse. (F) Aspect ratio(a/b) in a symmetric synapse.
Mentions: Results were obtained both for vesicles in each synapse separately and for all around 500 vesicles pooled together for asymmetric synapses. The second column in Table 1 shows that the mean surface areas of the synaptic vesicles are similar in all synapses. The histograms of shape characteristics in Figure 4 further show that the vesicles are far from spherical. Table 1 shows that the mean a/b ratio and mean b/c ratio appear to be considerably smaller than the mean a/c ratio for all asymmetric synapses. This also holds for the mean ratios for all vesicles considered jointly. These findings indicate that vesicles are of oblate ellipsoidal shape in the asymmetric synapses. On the other hand, in symmetric synapses the mean a/b ratio and mean b/c ratio appear to be very similar and considerably smaller than the mean a/c ratio. This indicates that the synaptic vesicles are of cigar ellipsoidal shape in the symmetric synapse.

Bottom Line: Statistics for marked point processes were employed to study spatial interactions between vesicles.We found that the synaptic vesicles in excitatory synapses appeared to be of oblate ellipsoid shape and in inhibitory synapses appeared to be of cigar ellipsoid shape, and followed a systematic pattern regarding their orientation toward the active zone.Moreover, there was strong evidence of spatial alignment in the orientations of pairs of synaptic vesicles, and of repulsion between them only in excitatory synapses, beyond that caused by their physical extent.

View Article: PubMed Central - PubMed

Affiliation: Computer Science Department, University of Copenhagen Copenhagen, Denmark.

ABSTRACT
The spatial interactions of synaptic vesicles in synapses were assessed after a detailed characterization of size, shape, and orientation of the synaptic vesicles. We hypothesized that shape and orientation of the synaptic vesicles are influenced by their movement toward the active zone causing deviations from spherical shape and systematic trends in their orientation. We studied three-dimensional representations of synapses obtained by manual annotation of focused ion beam scanning electron microscopy (FIB-SEM) images of male mouse brain. The configurations of synaptic vesicles were regarded as marked point patterns, where the points are the centers of the vesicles, and the mark of a vesicle is given by its size, shape, and orientation characteristics. Statistics for marked point processes were employed to study spatial interactions between vesicles. We found that the synaptic vesicles in excitatory synapses appeared to be of oblate ellipsoid shape and in inhibitory synapses appeared to be of cigar ellipsoid shape, and followed a systematic pattern regarding their orientation toward the active zone. Moreover, there was strong evidence of spatial alignment in the orientations of pairs of synaptic vesicles, and of repulsion between them only in excitatory synapses, beyond that caused by their physical extent.

No MeSH data available.


Related in: MedlinePlus