The “Electro-dermal Point” (Ishikawa) is a circumscribed skin area with a dimension of about 0.5×0.5mm or minor where electric resistance is at an order of as little as 1/100th of the surrounding skin areas.
According to Ishikawa's reports the point is closely connected with viscerocutaneous reflex and “Keiketsu” in the oriental medicine.
But according to Kubota the point shows no qualitative difference from electrically induced insulation-broken skin areas in I-T & V-I relationships and recovery curves. It is a circumscribed skin area with electrically low resistance, easy to break down, which can be secondarily produced by the a application of the Electrodermometer which was devised by Ishikawa to detect the point.
The “Differential Dermal Point” is a skin area with marked potential difference to surrounding skin area and detected by the “Differential Dermometer” which measures the potential difference between the two tiny electrodes with fixed distance of 1.5mm closely applied on the skin, where a weak current of about 0.15μA (100-400μV) flows, induced by domestic alternating current or so.
Therefore there is no risk of inducing break down of skin insulation by the use of a “Differential Dermomer” in contrast to the application of an “Electro-dermometer”.
By the latter procedure about 5-18 Volt (D. C.) is charged between the two electrodes.
The purposes of this paper were to investigate:
1. Measuring conditions of the “Differential Dermometer”.
2. Microscopic findings of the “Electrodermal Points” and “Differental Dermal Points” in human subjects.
3. Correlation between the Electrodermal Point, Differential Dermal Point and the skin areas given intracutaneously vaso-constrictors (adrenaline. atropine) or vasodilatators (pilocarpine, histamine, serotonin).
4. Electrodermal Points and Differential Dermal Points on the abdomen of rabbits.
5. Correlation of Differential Dermal Points and “Keiketsu” in the oriental medicine.
The results were as follow:
1. Differential-dermometer was modified in this study from the original type. One electrode with larger dimension was connected to filament side and earthed. Pottential difference read by the application of the modified Differential-dermometer was roughly proportional to the skin resistance at the electrode connected to the grid. No marked change in potential difference was observed by changing the distance of the indifferent electrode from the different electrode (grid side).
2. Differential-dermal points were found more abundantly than electro-dermal points. Every electro-dermal point showed the characteristics of differential dermal point but not vice versa.
The histological findings of the electro-dermal points and the differential dermal points on the trunk showed that there were an epidermal intercellular edema, pyknosis, small wedge-formed necrosis and scar at the prickle-cell layer corresponding to the flow area of a subcutaneous arteriole. But some of the differential dermal points revealed no marked change histologically. Electro-dermal points on the extremities showed also no marked histological change.
3. Thick distribution of differential-dermal points was observed surrounding the mamillae of rabbits.
4. While the effects of the vasoconstrictors given intracutaneously continued, the skin area was liable to change into electro-dermal point by the application of an electrodermometer and to show characteristics of differential dermal points.
5. The differential-dermal points coincide with “Tai-en”, “Shin-mon” and “Tai-ryo” in the fore-arms.

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