Glycogen-containing lysosomes and glycogen loss in the cardiocytes of embryonic and neonatal mice.
In the mouse embryo the transformation of mesenchymal cells into cardiac myocytes was seen to be indicated by the appearance of glycogen and myosin filaments. In the early force-producing muscle cells, but particularly in the specialized cells destined to become part of the A-V conduction system, the glycogen became abundant. With maturation of the embryo and differentiation of the cardiocytes, the glycogen content decreased in both the force-producing and "conducting" muscle fibers. In late fetal life, and spectacularly after parturition, the loss of glycogen content in the specialized cells was accompanied by the appearance of glycogen-containing lysosomes. Changes in the structure of such lysosomes indicated ongoing dissolution and uncommon use of metabolizable glycogen.
D000818:Animals; D001283:Atrioventricular Node / Q000166:cytology; D002036:Bundle of His / Q000166:cytology; D002454:Cell Differentiation; D005260:Female; D006003:Glycogen / Q000378:metabolism*; D006346:Heart Septum / Q000166:cytology; D008247:Lysosomes / Q000378:metabolism*; D051379:Mice; D008854:Microscopy, Electron; D008929:Mitochondria, Heart / Q000378:metabolism; D009200:Myocardial Contraction; D009206:Myocardium / Q000166:cytology*; D011247:Pregnancy
D006003:Glycogen