Terminal diversification of the myocyte lineage generates Purkinje fibers of the cardiac conduction system.

摘要: The rhythmic contraction of the vertebrate heart is dependent on organized propagation electrical excitation through cardiac conduction system. Because both muscle- and neuron-specific genes are co-expressed in cells forming myocardial tissues, two origins, myogenic neural, have been suggested for this specialized tissue. Using replication-defective retroviruses, encoding recombinant beta-galactosidase (beta-gal), we analyzed cell lineage Purkinje fibers (i.e., peripheral elements system) chick heart. Functioning myocyte progenitors were virally tagged at embryonic day 3 incubation (E3). Clonal beta-gal+ populations cells, derived from myocytes infected E3 examined 14 (E14) 18 (E18) days incubation. Here, report that a subset clonally related differentiates into conductile fibers, invariably close spatial association with coronary arterial blood vessels. These clones, containing working did not incorporate contributing to tissues central system (e.g. atrioventricular ring bundles). In quantitative analyses, found whereas number nuclei per clone more than doubled between E14 E18, fiber remained constant.(ABSTRACT TRUNCATED AT 250 WORDS)