The microvasculature in skeletal muscle. IV. A model of the capillary network.

A reconstruction of the capillary network in the rat spinotrapezius muscle was carried out using carbon-filled specimens. A new branching schema for the capillaries, consisting of individual capillary bundles, is proposed. Each bundle is provided with blood through transverse arterioles and drained by collecting venules. A capillary bundle may be divided into capillary bundle elements consisting of a transverse arteriole, a collecting venule, and the intermediate capillary network. A set of seven independent network parameters are proposed and measurements are provided for two rat strains: Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR). A comparison of network parameters indicates a multifaceted difference between the strains. In SHR the number of capillary cross-connections is reduced, individual capillary lengths are greater, and vessel diameters are slightly larger.