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Structure of Cardiac Muscles

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Cardiac muscle, or myocardium, is a specialized type of muscle found exclusively in the heart. Its unique structural and functional characteristics enable the heart to perform its vital role of pumping blood throughout the body continuously and rhythmically. The cardiac muscle cells, or cardiomyocytes, possess an endomysium and perimysium but do not have an epimysium.
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Related Experiment Video

Updated: Jul 17, 2026

Generation of Murine Cardiac Pacemaker Cell Aggregates Based on ES-Cell-Programming in Combination with Myh6-Promoter-Selection

Generation of Murine Cardiac Pacemaker Cell Aggregates Based on ES-Cell-Programming in Combination with Myh6-Promoter-Selection

Published on: February 17, 2015

Dynamic Cellular Integration Drives Functional Assembly of the Heart's Pacemaker Complex.

Michael Bressan¹, Trevor Henley¹, Jonathan D Louie²

¹Department of Cell Biology and Physiology, McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.

|May 24, 2018

Summary

The sinoatrial node (SAN), the heart's pacemaker, forms as mesenchymal cells integrate with and surround heart muscle. This process is essential for the SAN's structure and sustained rhythmic heartbeats.

Keywords:

cardiac morphogenesis cardiac pacemaker cell proepicardium sinoatrial node

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Generation of Murine Cardiac Pacemaker Cell Aggregates Based on ES-Cell-Programming in Combination with Myh6-Promoter-Selection

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Area of Science:

Cardiovascular Biology
Developmental Biology
Cardiac Electrophysiology

Background:

The sinoatrial node (SAN) is the heart's primary pacemaker, responsible for initiating rhythmic contractions.
Its cellular composition and the microenvironment have been studied, but the developmental processes governing its tissue-level assembly remain unclear.

Purpose of the Study:

To elucidate the biological processes driving the tissue-level assembly of the sinoatrial node.
To understand how the SAN's unique structural features and microenvironment are patterned during development.

Main Methods:

Investigated the developmental origins of SAN structural components.
Examined the integration of mesenchymal cells with pacemaker myocardium during SAN formation.
Assessed the functional necessity of this integration for electrogenic signal generation.

Main Results:

SAN structural features arise from the integration of proepicardium-derived mesenchymal cells with pacemaker myocardium.
This integration actively remodels the developing SAN.
The process is critical for sustained electrogenic signal generation and propagation.

Conclusions:

The microenvironmental architecture of the SAN is actively patterned during development.
Proper cellular arrangement and integration are crucial for cardiac pacemaker biorhythmicity.
This study reveals a novel mechanism for SAN tissue assembly and function.