. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ELECTRICAL ACTIVITIES OF SPIROCODON 387 between 5 and 10 mV, were common in the 26 cases studied. They always cor- responded either to SMPs or to the slow phase of QSCPs (Fi It is quite clear that they originate in certain ectodermal cells of the radial streaks because the fine tips of electrodes used could not penetrate the opaque mes >ea without being damaged. To estimate membrane resistance changes during the pulses, current pulses were delivered through a balanced bridge circuit but unexpectedly, no changes were obser
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ELECTRICAL ACTIVITIES OF SPIROCODON 387 between 5 and 10 mV, were common in the 26 cases studied. They always cor- responded either to SMPs or to the slow phase of QSCPs (Fi It is quite clear that they originate in certain ectodermal cells of the radial streaks because the fine tips of electrodes used could not penetrate the opaque mes >ea without being damaged. To estimate membrane resistance changes during the pulses, current pulses were delivered through a balanced bridge circuit but unexpectedly, no changes were observed in four cells measured ( Fig. 8B). However, inje; ion of positive current of about 10 s A through the internal electrode often induced slow positive deflection similar to the ectodermal large pulses (Fig. 8D), resembling intracellularly recorded subthreshold pulses in the epithelio-muscular cell of Nanomia (Spencer, 1971). Pulses could not be evoked by delivering current extracellularly through such fine electrode tips. Even using electrodes with much larger tips of 20-30 /^m, current of 10~5 A was needed. Furthermore, resistances were measured before and after withdrawal of the inserted electrode and a mean difference of Mfi (variation, 3-4 Mfi) was obtained in five measurements. Therefore, it appears likely that the ectodermal large pulses are recorded within cells having an excitable membrane. Similarly, the experimental results indicate that SMPs and the slow phase of QSCPs originate in the same kind of cells and can therefore be regarded as extracellular forms of the ectodermal large pulses. The. s pmV 100msec. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report 1907/08-1952; Lillie, F
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
