Table 1.

Nerve terminal ultrastructure for mutant and control samples

Axon 1Axon 2Axon 1Axon 2
Terminal length sampled (μm)
Surface area sampled (μm2)76.871.0109.180.8
Number of varicosities sampled3546
Number of synapses analyzed41374448
Mean synapse size (μm2)0.310.270.920.66
Total number of active zones303611390
Estimated active zones per varicosity1072815
Active zones/terminal surface area (#/μm2)
Active zones/terminal length (#/μm)
Active zones per synapse0.
Number of synapses with:
0 active zones17 (41%)13 (35%)5 (11%)13 (27%)
1 active zone20 (49%)14 (37%)17 (39%)10 (21%)
2 active zones3 (7%)7 (19%)6 (14%)12 (25%)
3 or more active zones1 (2%)3 (8%)16 (36%)13 (27%)
  • These data are the mean values obtained from two control and three mutant series of sections from abdominal segment 4. Nerve terminal lengths are different for the two axons within a genotype because of branching of the individual axons.