Abstract
There is a fairly extensive literature on this subject, 1 which cannot be discussed here even though recent work on the contraction of smooth muscle and the production of tonus pays but scant attention to its possible significance. In this place only those findings will be reported, which, as far as I know, have not been described in smooth muscle and connective tissue.
The material studied was the stomach of the frog, colon of the guinea pig, caecum of the rabbit, and duodenum and lower small intestine of the dog. The chief fixative was Orth's solution. The sections were cut from paraffin blocks. 2 The most instructive slides were obtained when the plane of the section was tangential to the surface of the gut or parallel to the direction of the spiral fold in the rabbit's caecum.
Results: Muscle nuclei with a spiral or rather helicoid twist may be observed in every section, particularly if the gut was well contracted. They are most numerous at or near Auerbach's plexus, both in the circular and longitudinal layers. The twist may be a right or a left screwthread, both types occurring in the same field. In numbers of instances the same nucleus showed a right twist in one section and a left twist at the other end. Occasionally the transition site of one twist to the other was beautifully apparent, and on a miniature scale, the same as shown by the accompanying figure 1, observed in white fibrous tissue. The closeness of the twist varied: in the pale vesicular nuclei there was either no twist or 1-2 shallow spiral grooves; with increase in the number of twists the nucleus stained more and more densely, became thinner and often looked like a small closely coiled spring; the densely staining, slender, rod-shaped nuclei showed either a faint twist of steeper pitch than the close spirals or none at all; the pale staining, long, rod-shaped nuclei showed no twist in general.
Get full access to this article
View all access options for this article.