Figure 6.

Size distributions of randomly oriented, simulated synapses after projection onto a two-dimensional surface. a, Average member of a group of ellipsoid, slightly concave objects used in the simulation. The semi-axes of the ellipsoids were varied according to parameters described in the text so as to produce a population of 20,000 structures that differed in size and shape. b, Average member of a group of ovoids used to simulate a second population of synapses. As with the first group, the axes of the ovoids were independently varied so as to produce a collection of objects that varied in size and shape. The mean circumference of the ovoids was the same as that for the ellipsoids. c, Distribution of areas of the projected two-dimensional images for the two populations of simulated synapses. Both populations were oriented randomly in a layer that was as thick as the longest simulated synapse and projection was made along the axis perpendicular to the layer. The mean area of the projected ovoids was 60% greater than that for the projected ellipsoids. The frequency distribution of ellipsoids approximated a Poisson, whereas that for the ovoids was more Gaussian.