. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. PROSOBRANCH OSPHRADIUM 183 a-FMRFa a-LEnk NADPHd. B Figure 9. Schematic representation of FMRFa- and LEnk-immu- noreactive and NADPHd-positive elements in the left half of the os- phradia of Littorina littorea (A) and Bucdmim undatum (B). bivalve mollusc Anodonta. LEnk- and FMRFa-ir cells were found abundantly distributed in the gill epithelium. Correspondingly, bivalves have been described as having poorly differentiated osphradial sensory system (Sokolov and Zaitseva, 1982; Haszprunar, 1987). These findings lead us to spec
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. PROSOBRANCH OSPHRADIUM 183 a-FMRFa a-LEnk NADPHd. B Figure 9. Schematic representation of FMRFa- and LEnk-immu- noreactive and NADPHd-positive elements in the left half of the os- phradia of Littorina littorea (A) and Bucdmim undatum (B). bivalve mollusc Anodonta. LEnk- and FMRFa-ir cells were found abundantly distributed in the gill epithelium. Correspondingly, bivalves have been described as having poorly differentiated osphradial sensory system (Sokolov and Zaitseva, 1982; Haszprunar, 1987). These findings lead us to speculate that the osphradium may have orig- inated as a site of concentration of epithelial sensory ele- ments that predated the organ itself. The degree of spe- cialization might then have increased progressively during evolution. Note in this connection that, although no LEnk-ir cells were found in or below the epithelium, in- cluding the mantle epithelium, of pulmonate molluscs (Sakharov el ai. 1993), the concentration of LEnk-ir ele- ments in their osphradial epithelium is extremely high (Nezlin f/a/.. 1994). MEnk-ir cells were found in a similar position as the LEnk-ir cells only in the highly evolved osphradium of Buccinum. In all other prosobranch species, MEnk-ir cell bodies and fibers were distributed in a uniform manner within and around the ganglion. The sensory nature of these cells has not been established, but the involvement of additional sensory subsets of neurons in more sophis- ticated osphradia is suggested by this finding. NO attracts wide attention as a novel signal molecule. A possible role for this intercellular messenger in ol- factory signal processing has been recently discussed by Breer (1993) and Breer and Shepherd (1993). The os- phradium of the pulmonate snail Lvmnaea st agnails appears to have been the first invertebrate structure wherein NADPHd-positive cells were demonstrated by a histochemical method and synthesis of NO was proved biochemically (E
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
