Table 1.

Function and morphology of nociceptors discussed in this review

Organism	Cell type	Modalities	Multi-dendritic	Tilingc
C. elegans	PVD	Mechanical, thermal	Yes	Yes
	FLP	Mechanical, thermal	Yes	Yes
	ASH	Mechanical, chemical	No	NA
Drosophila	DA-IV	Mechanical, thermal, light, chemical (cytotkines)	Yes	Yes
Mammalsa	C-fibers	Mechanical, thermal, chemical	Yes	No
	Aδ-fibers	Mechanical, thermal	Yes	?
Hirudo medicinalis	N- Cells	Mechanical, thermal, chemical	Yes b	No
	P-Cells	Mechanical (pressure)	Yes	No

^aMammalian nociceptors are heterogeneous. Both C-fibers and Aδ-fibers include multiple types of neurons having different functions, properties, and molecular markers

^bN-cells appear to be multi-dendritic, however, detailed analysis of their morphology is currently lacking

^cAbbreviations: NA, data not available.