Figure 12

Organization of musculature in 4-day-old (A-C, E-F) and metamorphic (D) Phoronopsis harmeri . A. Borders with desmosome-like contacts (open arrowheads) between muscle cell (mc) of the tentacle elevator base and cell of the tentacular coelom lining (cl). B. Cross section of the tentacles with muscle cells of the tentacle elevator base, cells of the coelomic lining, and blood vessel (bv). Desmosomes between two muscle cells and between the muscle and coelothelial cells are indicated by opened arrowheads. C. Coelomocites include parts of degenerated muscular cells (double arrowheads). D. Longitudinal section of esophageal muscular lining with desmosomes (arrowheads) between cells. E. Coelomic lining (cl) of the trunk coelom (tc) and esophageal musculature (mc); longitudinal section of the esophagus (eso). F. Semi-thin cross section of the tentacle with blood vessel and degenerated muscles (dm) and erythrocyte (er) inside, base of the tentacle elevator (teb), coelomic cavity (c2) with coelomocites (cc), cells of the coelomic lining contain huge phagosomes (closed arrowheads).