Qualitative and quantitative study of wound healing processes in the coelenterate, Plexaurella fusifera: Spatial, temporal, and environmental (light attenuation) influences

Following injury the Caribbean soft coral, Plexaurella fusifera, forms an e pithelial front containing amoebocytes and zooxanthellae, a photosynthetic endo symbiont. Amoebocytes may be responsible for extruding the connective mesogleal fibers necessary for regeneration of tissue and zooxanthellae may provide the energy for repair. This study examined the effects of time, sp ace, and environment (light attenuation) on around healing in this coral sp ecies and quantitatively confirmed the increase of amoebocyte concentration s in the injured area. A wound was made on coral brachlets by removing simi lar to 4.5 mm of coenenchyme. At assigned times after injury, samples were collected for gross morphological and histological evaluation, in which amo ebocytes and zooxanthellae concentrations were quantified within 0.009 mm(3 ) of tissue. Overall amoebocyte numbers within uninjured and wounded tissue were similar. However, when numbers of amoebocytes per area of injured tis sue were calculated and compared to those of uninjured tissue, 82.4% more a moebocytes occurred at distances 0-0.5 mm from the wound edge, while areas of tissue >2 mm from the wound edge were occupied by fewer amoebocytes. Ove rall increases in concentrations of zooxanthellae also occurred within woun ded coral, but no apparent temporal, spatial, or light-related pattern was detected. Therefore, this study supports the conjecture that amoebocyte acc umulation at a wound site is an effect of cells migrating from uninjured ti ssue adjacent to the wounded edge. In addition, this movement occurs regard less of light attenuation. Light, which in this study was confined to range s between 70 and 545 mu E s(-1) m(-2), did not significantly affect the wou nd healing process in regard to either closure or cellular concentrations. (C) 1999 Academic Press.