[Innervation of the anterior byssus retractor muscle (ABRM) in Mytilus edulis L. and in Mytilus galloprovincialis Lmk. V. Cytochemical localization of cholinesterase activities (author's transl)].

Specific and non specific cholinesterase activities were demonstrated in the ABRM of Mytilus edulis L. and Mytilus galloprovincialis L. by means of different techniques. The results were found identical for both species: neuromuscular junctions "en grappe"-type scarely distributed within the ABRM, contain AChE. According to the histochemical inhibition tests, (a) the eserine inhibits AChE activity of the ABRM with a level of 5-10(-5) M or higher, (b) the ChE non specific activities are inhibited by iso-OMPA level between 5.10(-5) to 10(-4) M. The histo- and cytochemical observations were completed by showing the existence of neuromuscular junctions containing small clear vesicles: they probably are the morphological support for ACh presence. Moreover, specific and non specific ChE activities were localized in the glio-interstitial cells. AChE precipitates were developed along the ABRM sarcolemma, some muscle mitochondria and in the intercellular spaces remain enigmatic.