. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. n if N \ structures are essential body components that eventually form the body cavity in adult organisms, ultimately sur- rounding the digestive and reproductive organs. Coelomo- cytes (located within the coelom) have been reported to participate in regenerative processes in adult echinoderms (Thorndyke ct ai, 1999). In contrast, we found that bisected larvae, lacking coelomic pouches in their anterior regions, completed regeneration. Thus, coelomocytes apparently do not play a critical role in larval regeneration. In adult
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. n if N \ structures are essential body components that eventually form the body cavity in adult organisms, ultimately sur- rounding the digestive and reproductive organs. Coelomo- cytes (located within the coelom) have been reported to participate in regenerative processes in adult echinoderms (Thorndyke ct ai, 1999). In contrast, we found that bisected larvae, lacking coelomic pouches in their anterior regions, completed regeneration. Thus, coelomocytes apparently do not play a critical role in larval regeneration. In adult asteroids, regeneration is initiated by a prolifer- ation of epidermal cells forming a mesenchymatous blast- ema, which later gives rise to the missing body structures (Candia Carnevali and Bonasoro, 1994; Bonasoro et 1998; Thorndyke el ai, 1999). Our observations demon- strate that regenerative processes occur in a similar fashion in planktotrophic asteroid larvae. Our microscopic exami-. Figure 6. Two weeks after surgical removal of the far anterior tips of the bipinnariae of Pilaster oc/irac VIM, the anterior tips showed no signs of regeneration of the larval body but continued to actively swim, while the posterior portions had partially regenerated the missing tips. (A) Anterior tip (including axocoel) immediately after bisection. (B) Anterior tip 2 weeks after bisection. (Cl Posterior portion approximately 1 week after bisection. Scale bars = 50 fim in (A)-(B), 200 in (C). •• Discussion The present study demonstrates that planktotrophic larvae of the asteroids Lituliu foliolata and Pisaster ochraceus possess extensive regenerative capacities regardless of their developmental stage. In early and mid-stage surgically bi- sected larvae, both species regenerated missing body com- ponents within 2 weeks; and no mortality occurred due to bisection, a result similar to our previous observations (Vickery and McClintock, 1998). Mesenchyme cells pos- sessing pseudopod
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
