Localization of a fibronectin-like molecule in the ovotestis of the snail Helix aspersa

Summary An antifibronectin antibody has been prepared which recognises a fibronectin-like substance isolated from Helix aspersa hemolymph. By use of the indirect immunofluorescence technique, the distribution of fibronectin in embryos and in the ovotestis at selected development stages from hatching to the adult has been investigated. In embryos, the basement membranes and the epithelia were immunoreactive, whereas the mesenchyme and the gonadal rudiment were not. After hatching, the fibronectin was present in ovotestis. It was localized on the epithelia of gonadal acini and at the periphery of the periacinar vesicular tissue. This adhesive molecule is present on the nurse cells, which sustain the group of male cells, while it is absent on differentiating male cells in the lumen of acini. The membrane of oocyte did not exhibit fluorescence. By contrast the surface of follicular cells were clearly labelled. Inside the vitellogenic oocytes, granular fluorescence was also observed.The participation of fibronectin in gonadal organogenesis is discussed in relation to cellular adhesion and movement. Its role in the metabolic exchanges between the germinal cells and the surrounding tissues is suggested.