Coronary Circulation in Dog's Heart
Demonstration of Muscle Sphincters in Capillaries
A study of the capillary structure in the myocardium of the dog reveals three divergent types which can be distinguished on the basis of the presence or absence of sphincter muscle cells located in a position comparable to that occupied by the media of the larger vessels. The true capillary is completely wanting in muscular elements; the precapillary contains one or more muscle cells at the segmental area of attachment with the parent vessel; and the metarteriole contains one or more muscle cells located at irregular intervals along the vessel.
- Received November 3, 1958.
- © 1959 American Heart Association, Inc.