ONTOGENESIS OF MITOCHONDRIAL RETICULUM IN RAT DIAPHRAGM MUSCLE

  • 1 January 1981
    • journal article
    • research article
    • Vol. 25  (1) , 175-181
Abstract
Ontogenesis of mitochondrial reticulum discovered in rat diaphragm was studied with an EM by the serial section technique. The amount of mitochondrial material in the diaphragm of rat embryos was small. There are rare inclusions of single mitochondria which form columns paralleling the long axis of muscle fiber. After birth, a progressive increase in the amount of mitochondrial material takes place. This process is accompanied by the appearance of new components inherent in the unitary system of mitochondrial reticulum, namely, mitochondrial junctions, and branches and tubules of mitochondrial material paralleling Z-discs and localized on the levels of the isotropic regions of sarcomeres. The 1st mitochondrial junctions appeared as early as on the 2nd day and the mitochondrial branches between the 2nd and the 9th day of postnatal development. For a 1-mo.-old rat, a 3-dimensional model of a part of mitochondrial reticulum corresponding to 1 sarcomere was reconstituted. It revealed columns of mitochondrial material crossing the anisotropic region of sarcomere. Such columns connect 2 networks of mitochondrial profiles localized on the level of 2 isotropic regions of sarcomere. Formation of mitochondrial reticulum is completed within 2 postnatal mo.