Transverse Tubule Apertures in Mammalian Myocardial Cells: Surface Array

Abstract
The technique of " freezeetching" tissues for electron microscopy has permitted observation of the external apertures of the transverse tubules. The apertures appear on the cell surface in approximately parallel rows, which can be interpreted as corresponding longitudinally to the spaces between the myofibrils and transversely to the Z regions of the myofibrils.