Abstract
In order to clarify why the rhythmical contractions of the postnatal intestine proceed downwards, experimental study of fetus was performed as follows:
Human and bovine intestines in several fetal stages were observed histologically; the movements of the intestinal specimens kept alive in Tyrode's solution were observed under the microscope and recorded with cinematographic method, and the action potentials thereby produced were also traced from the intestines; regarding the pathologic physiology, the function of dilated bovine intestines with their contents increased with Tyrode's solution injected into them was observed.
Around the8th week of fetal life, the human intestine has circular muscle, but neither longitudinal muscle nor intramural nerve developed in its wall, and shows distinct automatic contraction-ring, which travels either in the orthoperistaltic or anti-peristaltic direction. From a single original contraction-ring often occur two divergently travelling peristalsises described above. This fact proves that in the early stage of fetus, without any intramural ganglion developed, peristalsis exist but the direction of peristaltic conduction is not decided.
In and after the9th week, the waves of contraction, some proceeding upwards and others downwards, are intensified by degrees with the development of longitudinal muscle and intramural ganglion.
The anti-peristaltic movements become more and more indistinct later on till in and after the19th week of fetal life and the movement of the intestine are predominantly ortho-peristaltic, but the rudimentaryfunction of anti-peristalsis never eradicated.
Experimentally, a bovine intestinal specimen in the later fetal stage readily starts anti-peristaltic movement, especially when its content becomes accumulated
In electrophysiological observation the ortho-or anti-peristaltic contraction is accompanied by action potential; and a single contraction-ring corresponds to one group of spikes.
