The collagen network of the heart.

An extensive collagen skeleton in the myocardium is clearly demonstrable by scanning electron microscopy. This system mechanically connects myocytes to contiguous myocytes, connects myocytes to contiguous capillaries, and is responsible for orienting myocytes into anatomical units. The extent and location of the system involves it in a variety of physical parameters of the heart under both normal and abnormal conditions. The myocyte to myocyte collagen struts may provide for sarcomere alignment from cell to cell, ensure equal stretch of contiguous cells, and prevent slippage of adjacent cells. The numerous myocyte to web network connections would ensure that the entire group of cells function in a consistent fashion. The origin and course of the myocyte to capillary collagen struts could account for capillary patency during systole in the presence of high ventricular wall pressures. The complex web network surrounds groups of myocytes and is mechanically coupled to the contained myocytes. The loose collagen connections between groups easily permits slippage and rearrangement of groups of cells as expected in acute dilation. The web network itself could be the site of some of the viscoelastic properties of the heart.