Retrogradely labeled SON neurons
| Ipsilateral SON | Contralateral SON | |
|---|---|---|
| Fluorescein-labeled | 372 | 22 |
| Rhodamine-labeled | 743 | 29 |
| Double-labeled | 0 | 0 |
| Total labeled cells | 111 (96%) | 51 (4%) |
Number of labeled SON cells in four animals after one tracer was injected on one side of the brainstem, and the other tracer was injected into the same area on the other side of the brainstem.