ELECTRON MICROSCOPY ON A GORGONIAN CORAL, ANTHOPLEXAURA DIMORPHA

Abstract

Gorgonian corals usually have arboreal colonies with many slender stems and branches. Each of these stems or branches is composed of a horny axis and of an outer cover of living portion with numerous calcareous spicules. In a previous paper covering a gorgonian, Euplexaura erecta, we have described only the spicules but not the horny axis (2). In the present work both spicules and the axis have been observed in the same section under an electron microscope. The axis of the tip portion of a branch is much thinner than that in the previous species. The axis shows a characteristic structure with longitudinal arrangements of bundles of keratinous fibrils which are derived from fibroblasts on the axis surface. The process of spicule formation is somewhat different from that in the previous species.