median 1: range 0.05-10.1 µm^3
||Turtle Trachemys scripta elegans
||Yeow MB, Peterson EH. Active zone organization and vesicle content scale with bouton size at a vertebrate central synapse. J Comp Neurol. 1991 May 15 307(3):475-86 DOI: 10.1002/cne.903070310 p.478 left column bottom paragraphPubMed ID1856332
||Abstract: "The present study has addressed this issue [that axons differ in the size of their synaptic boutons] by using three-dimensional reconstruction of serial thin sections to examine the ultrastructure of synaptic boutons that vary in size. [Investigators’] observations are based on complete or near-complete reconstructions of 53 synaptic boutons contacting large neurons in the ventromedial gray matter of the upper cervical spinal cord (probable neck motor neurons)."
||P.478 left column bottom paragraph: "[Investigators] characterized the size of reconstructed boutons in terms of their volume and total apposition area ((total area of membrane apposed to the motor neuron), cf. Materials and Methods). The distribution of both variables is shown in Figure 2. Bouton volume varies widely (Fig. 2A range: 0.05-10.1 µm^3 median = 1 µm^3 interquartile range = 1.69 µm^3), but most boutons are small. For example, 93% have volumes of ≤4 µm^3, 74% are ≤2 µm^3."