Recognizing synapses in the zfish dataset
To identify synapses in zfish cells, look for 2 things:
- A short stretch of border between 2 cells, that is darker and thicker than the rest of the border.
- An area of increased neurotransmitter vesicle density on one side of the dark border.
When you've identified a synapse, it should be easy to tell which side of the border is the axon and which is the dendrite. The area of higher vesicle density marks the presynaptic neurite, or axon. The other side is the postsynaptic neurite, or dendrite.
Note: there is such a thing as postsynaptic density, but I'm not sure if that is visible in zfish slides. Ironically, the presynaptic side is visibly denser than the postsynaptic side due to the neurotransmitter vesicles.