Attachment to the substrate by soft coral fragments: Desmocyte development, structure, and function

Pieces cut from colonies of the soft coral Dendronephthya hemprichi exhibited rapid and effective attachment to hard surfaces. Attachment involved development of root-like processes (RLPs), which appeared at the basal part of the fragment 4 days after its removal from the colony. The fine structural changes and cascade of cellular events occurring in the RLP before and after attachment were studied using SEM, TEM, and LM. The epidermis of the RLPs is actively involved in the attachment process and several distinct phases are documented: appearance of numerous oval vesicles, extrusion of these vesicles resulting in the formation of an outer layer composed of extracellular organic matrix and organellar debris, which functions as an adhesive device leading to initial attachment. The latter phase was followed by the formation of desmocytes, which develop in the RLP epidermis and function as anchoring devices, mediating the firm attachment of the fragment to the substrate. This is the first evidence among anthozoans that desmocytes play an active role in anchoring tissue to substrate and thus extends the range of functions exhibited by desmocytes among anthozoans.