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THE ULTRASTRUCTURE OF MAMMALIAN CARDIAC MUSCLE

R J Stenger1, D Spiro

  • 1Department of Pathology, Harvard Medical School, and the Edwin S. Webster Memorial Laboratory of the Department of Pathology, Massachusetts General Hospital, Boston.

The Journal of Biophysical and Biochemical Cytology
|October 30, 2009
PubMed

Insights

Mammalian cardiac muscle shares a filamentous fine structure with striated skeletal muscle, featuring similar sarcomeres and filament arrangements. Further research is needed to fully understand the functional implications of this cardiac muscle structure.

Area of Science:

  • Cardiovascular Biology
  • Muscle Physiology
  • Cellular Ultrastructure

Background:

  • Previous studies described the fine structure of striated skeletal muscle.
  • Understanding cardiac muscle structure is crucial for comprehending heart function.

Purpose of the Study:

  • To investigate and describe the filamentous fine structure of mammalian cardiac muscle.
  • To compare the cardiac muscle structure with that of striated skeletal muscle.
  • To elucidate the structural components of cardiac cells, including sarcoplasmic reticulum and intercalated discs.

Main Methods:

  • Papillary muscles from rat and dog hearts were fixed to prevent shortening.
  • The muscle tissue was embedded in araldite or methacrylate.
  • Various staining techniques were employed for electron microscopy.

Main Results:

  • Mammalian cardiac muscle exhibits a filamentous fine structure analogous to striated skeletal muscle.
  • Sarcomeres are composed of interdigitating thick and thin filaments within the A band.
  • Similar filament ratios and arrangements were observed as in skeletal muscle.
  • Detailed descriptions of cardiac cell components, including surface membranes, mitochondria, nuclei, sarcoplasmic reticulum, and intercalated discs, were provided.
  • Deep sarcolemmal invaginations were frequently observed, potentially explaining cardiac fiber branching.

Conclusions:

  • The filamentous structure of mammalian cardiac muscle is highly conserved and similar to skeletal muscle.
  • The functional significance of the observed filament array requires further investigation.
  • Structural details of cardiac cells, particularly the sarcoplasmic reticulum and intercalated discs, offer insights into cardiac muscle mechanics and organization.

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