Fig. 1

Diagram of the leech CNS. Upper diagram shows the location of the leech CNS in the animal. Lower Diagram shows a fragment of two ganglia and connective tissues. Each ganglion contains four packet glial cells enveloping neuronal cell bodies. The axons go through the neuropil and extend into connectives. Microglial cells are distributed in all ganglia and connectives tissues. The neuropil lies dorso-medially and contains two macroglial cells. The nervous system is enclosed in the outer capsule which is covered outside by a visceral layer of the endothelium (lining the ventral blood sinus). In addition, it is represented a lesion in the center of the connective tissues with a microglia recruitment and extracellular vesicle (EV) accumulation