Table 1.
Comparison of exocytosis in mast cells and neurons.
| Parameter | Mast cells | Neurons |
|---|---|---|
| Granules | Secretory lysosomes | Specialized secretory granules |
| Granule size | 300–1000 nm | 50 nm |
| Granule number | Up to 1000/cell | 200–500/nerve terminal |
| Ca2+ requirements | 1 μM | 200 μM |
| PKC requirement | Yes | No |
| Time frame of exocytosis | Minutes | Milliseconds |
| Recycling time | Long (hours to days) | Very short (seconds to minutes) |
| Site of release | Multidirectionala | Active zone |
| Release characteristics | One single release, up to 100% of total granular content; multigranular/compound mode | Multiple release one granule per fusion event |
aNote that under specific local conditions of stimulation, mast cells are able to deliver SG content within specific zones.