Intercellular connections in rabbit heart as revealed by quick-frozen, deep-etched, and rotary-replicated papillary muscle.

Rabbit papillary muscles were ultrarapidly frozen, fractured, deep-etched, and rotary shadowed. These techniques revealed the interstitial space where the complex network of fine microthreads that connect myocytes to each other and to collagen fibrils can be seen in a three-dimensional array similar to scanning electron micrographs but at a resolution attainable in freeze-fracture microscopy.