Leech Dissection: Step 7
The blood sinus has many swellings along its length. Each swelling contains a segmental ganglion (plural: ganglia) of the leech's nervous system.
![A close-up of the cut-open leech in the dissection dish. There are four pale swellings along the leech's blood sinus, which are labeled 'ganglia.'](images/dissection7/leech_step4d.jpg)
The blood sinus has many swellings along its length. Each swelling contains a segmental ganglion (plural: ganglia) of the leech's nervous system.