Table 1.
Nerve terminal ultrastructure for mutant and control samples
| Control | Mutant | |||
|---|---|---|---|---|
| Axon 1 | Axon 2 | Axon 1 | Axon 2 | |
| Terminal length sampled (μm) | 17.0 | 20.0 | 21.3 | 42.6 |
| Surface area sampled (μm2) | 76.8 | 71.0 | 109.1 | 80.8 |
| Number of varicosities sampled | 3 | 5 | 4 | 6 |
| Number of synapses analyzed | 41 | 37 | 44 | 48 |
| Complete | 32 | 31 | 30 | 27 |
| Incomplete | 9 | 6 | 14 | 21 |
| Mean synapse size (μm2) | 0.31 | 0.27 | 0.92 | 0.66 |
| Total number of active zones | 30 | 36 | 113 | 90 |
| Estimated active zones per varicosity | 10 | 7 | 28 | 15 |
| Active zones/terminal surface area (#/μm2) | 0.4 | 0.5 | 1.0 | 1.1 |
| Active zones/terminal length (#/μm) | 1.8 | 1.8 | 3.6 | 2.1 |
| Active zones per synapse | 0.7 | 1.0 | 2.6 | 1.9 |
| Number of synapses with: | ||||
| 0 active zones | 17 (41%) | 13 (35%) | 5 (11%) | 13 (27%) |
| 1 active zone | 20 (49%) | 14 (37%) | 17 (39%) | 10 (21%) |
| 2 active zones | 3 (7%) | 7 (19%) | 6 (14%) | 12 (25%) |
| 3 or more active zones | 1 (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.