Electrical Activities in the Subtentacular Region of the Anthomedusanspirocodon Saltatrix(tilesius)

Three types of cells—myoepithelial cells, nerve cells, and nematocytes—are found in the ectoderm of the subtentacular region except near the nerve ring. A single type of endodermal cell is identified in the endoderm of the subtentacular region except near the ring canal. 2. Three types of conductive pulses—QSCPs, SMPs, and TCPs—are recorded in the ectoderm. When recording electrodes are inserted into the endoderm, SMPs and the slow phase of QSCPs (negative pulses) are replaced by PEPs (positive pulses). 3. Using high-resistance electrodes, two types of pulses (ectodermal and endodermal large pulses) are recorded (presumably intracellularly) from the ectoderm and the endoderm, respectively. They probably originate in the myoepithelial cells and in the endodermal cells, respectively. 4. SMPs and the slow phase of QSCPs occur coupled with the ectodermal large pulses and appear to be generated in the same cells, as the extracellular forms of the latter. The quick phase of QSCPs is probably an event generated by nerves in the ectoderm. 5. PEPs occur coupled with the endodermal large pulses and may be generated in endodermal cells as the extracellular forms of the endodermal large pulses. 6. Pulses with extremely small amplitudes suggesting the presence of another conducting system can be recorded. 7. SMPs and QSCPs are different from the crumpling pulses of Spencer (1975).