Contributions to Zoology, 71 (1/3) 37-45 (2002) SPB Academic Publishing bv, The Hague Newly-discovered muscle in the larva of Patella coerulea (Mollusca, the of larval Gastropoda) suggests presence a extensor Peter Damen and Wim+J.A.G. Dictus Department ofExperimental Zoology, Utrecht University, Padualaan 8, 3584 CH Utrecht, Netherlands,
[email protected] Key words: Patella, Gastropoda, Mollusca, development, larva, muscle, antagonist, cell-lineage Abstract and Dictus and Damen (1997). The formation of the 3D-macromere, which acts as an organizer and The developmentofthe muscular system ofthe gastropod mollusc is responsible for the correct dorsoventral pattern- Patella has been thoroughly studied. As a result, two larval of the has been described ing embryo, by e.g. van the main and larval had been retractors, accessory retractor, den Biggelaar and Guerrier (1979), Arnolds et al. described in ofPatella. the larva These muscles were supposed (1983), Verdonk and van den Biggelaar (1983), to be responsible for the retraction of the larval body into the Martindale et al. and Damen and Dictus shell.Previously no larval extensors, which would be responsible (1985), The of function for the extension of the larval body out ofthe shell, have been (1996). analysis gene during early described. Using cell-lineage tracer injection and phalloidin development has been described by van der Kooij staining ofmuscles, anewly-discovered muscle is herein identi- et al. (1996, 1998), Damen et al. (1994), Damen fied in the larva of Patella coerulea. A functional model is and Loon Klerkx van (1996), et al. (2001), Lartillot presented in which two muscles areresponsible for the extension et al.