As fibras de Purkinje teñen formas variables, irregulares e raras, con expansións, e a miúdo envolven a outras fibras. Teñen un ou dous núcleos, abundantes mitocondrias e glicóxeno, pero as súas [[miofibrila]]s son relativamente escasas, periféricas, separadas e pouco ordenadas comparadas coas das fibras cardíacas normais (por iso a penas se contraen). Teñen extensas áreas de contacto mútuas e moitos desmosomas e tamén áreas con [[unión comunicante|nexos]], pero non os discos intercalares típicos das fibras musculares <ref>Fawcett D.W. Tratado de Histología. 11ª edición. Interamericana-Mc Graw Hill. Páxinas 306-310</ref>. Transmiten os impulsos a unha velocidade de 1,5 a 4 m/s, que é unhas 6 veces maior ca a velocidade de condución polas fibras do ventrículo <ref name="Guyton"/>.
Purkinje fibers are a unique end-organ [[cardiac]] extension of the [[Autonomic Nervous System]]. Further histologic examination reveals that these fibers are split into left and right trees as well as atrial and ventricular contributions. The electrical origin of atrial Purkinje fibers arrives from the [[Sinoatrial Node]]. The following electrical origin of the ventricular Purkinje fibers arrives from the [[AV node|Atrioventricular Node]].
Given no aberrant channels, the atrial and ventricular Purkinje trees are distinctly shielded from each other by [[collagen]] or the [[cardiac skeleton]].
The Purkinje fibers are uniquely dedicated to [[Sympathetic nervous system|sympathetic]] electrical depolarization of the right and left atria and ventricles. The Purkinje fibers are further specialized to rapidly conduct impulses (numerous [[sodium ion channel]]s and [[mitochondria]], fewer [[myofibril]]s than the surrounding muscle tissue). Purkinje fibers take up stain differently than the surrounding muscle cells, and, on a slide, they often appear lighter and larger than their neighbours. They are binucleated.
