Smooth Muscle Bands Research Articles

A sphincter in the umbilical ring of the rabbit.

DURING the course of some experiments on fœtal rabbits, a very marked constriction was observed in the umbilical cord at the umbilical ring; the abrupt narrowing in this region accompanied the closure of the length of the umbilical vessels in response to traction or to cooling of the cord. A circular band of smooth muscle in the umbilical ring region has been described for the horse1 but for no other animal, and Sir Joseph Barcroft suggested that the structure of the rabbit's umbilical cord should be studied in more detail.

Leiomyoma of the Oral Cavity

It is well known that leiomyomas of both benign and malignant form may arise from the smooth muscle of any of those parts of the alimentary tube which are provided with muscular coats. They are smoothly circumscribed tumors, sometimes nodular, which form masses in the wall of the tube and are rather prone to ulceration accompanied by severe hemorrhages, although they are not usually vascular. They are not painful. Leiomyoma is found also in the skin and subcutaneous tissues. Although uncommon, it is not really rare, for there are in the Surgical Pathology laboratory of Columbia University records and preparations of 38 cases. It occurs both as a solitary tumor and also occasionally in multiple form. A remarkable clinical feature is the frequent occurrence in the tumors of marked tenderness or pain, or both. The pain is sometimes of paroxysmal character. These skin leiomyomas have been traced to the various smooth muscle structures found in that organ, especially the muscular coats of vessels, the arrectores pilorum, musculi diagonales cutis, and the special muscles of the sexual spheres, while some of the tumors are undoubtedly dysontogenetic neoplasms. They may develop as solid tumors composed very largely of interlaced bands of smooth muscle with only an insignificant vascular supply, or they may have a large number of vessels with thick muscular walls. These vessels are peculiar, resembling no normal vessel, since the smooth muscle in the wall is disoriented instead of being arranged in definite coats, and often it interdigitates at its periphery with the smooth muscle of the tumor.