Fig. 8

Details of the lophophoral base of Cinctipora elegans. Semithin cross-sections, toluidine blue. a, b and d are progressive sections from proximal to more distal. a Lophophoral base at the insertion of the retractor muscles in slightly oblique section. Directly adjacent lies the cerebral ganglion with two thick lateral ganglia and a circum-oral nerve ring encompassing the pharynx. A thick extracellular matrix and intertentacular bases are present in the proximal part of the lophophoral base. b Slightly more distal section than in A in the area of the mouth opening. Distinct tentacular ‘coeloms’ or cylinders are distinguishable and are surrounded laterally by the intertentacular bases. Distinct coelomic cavities are not recognizable on light microscopical level and mostly show central cells that fill the lumen. c Detail of the area is seen in B showing the thick extracellular matrix in the tentacle bases. d Most distal and slightly oblique section of the lophophoral base. Note that tentacle bases are still interconnected on the left side of the image whereas on the right they are already separated. Note also globular secretion within the area of the mouth opening. Abbreviations: cc – central cells, cg – cerebral ganglion, con – circum-oral nerve ring, cw – cystid skeletal wall, ecm – extracellular matrix, ex – exosaccal cavity, in – internal perikarya of the tentacle innervation, int – intestine, itb – intertentacular base, lb – lophophoral base, lg – lateral ganglion, mo – mouth opening, ms – membranous sac, py – pylorus, rm – retractor muscle, st – separate tentacles (distally of the lophophoral base), ts – tentacle sheath