NADPH diaphorase (nitric oxide synthase) in the central nervous system of spiders (Arachnida: Araneida)

The distribution of NADPH diaphorase (nitric-oxide synthase) in the CNS of spiders was determined in 10 species of five families, applying enzyme histochemical technique on sections of fresh frozen, unfixed material. Positively reacting cells could be found only in the peripheral neuropil and along internal and external lamellae of all species studied. These cells were numerous and showed long and widespread arborizations in the ventral cord of orthognath species. The results obtained are discussed in view of possible glial functions of such cells and the relation of nitric oxide to other neurotransmitters in the condensed brain of the Araneida.