Satellite cells

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Group of neurons organised and located outside the central nervous system.

Satellite cells can either refer to a population of stem cells found in skeletal muscle that are essential for its regeneration, or a type of glial cell which form a thin sheath around neuronal cell bodies in ganglia of the peripheral nervous system.

Satellite glial cell

The cell bodies of neurons located in sensory and autonomic ganglia are each surrounded by a cellular sheath of small cuboidal cells, known as satellite cells. In light microscopy, usually only their nuclei are identifiable.

Their function is believed to involve the support of the neuron which they surround i.e., nourishment, insulation and regulation of their microenvironments.

Skeletal muscle satellite cell

Skeletal muscle satellite cells, commonly referred to as myosatellite cells, are small, inactive mononucleate cells located between the cell membrane (sarcolemma) and basement membrane of mature skeletal muscle fibers. They are relatively small cells with minimal cytoplasm making them difficult to identify under light microscopy.

Myosatellite cells act as ‘reserve’ population of undifferentiated precursor cells which are responsible for the regeneration of skeletal muscle, albeit in a limited capacity. After injury, a portion of the normally quiescent myosatellite cells become active and begin to proliferate. Some daughter cells will remain as myosatellite cells, while others will become myoblasts – the progenitor cell for mature skeletal muscle fibers (myocytes). They are capable of joining existing muscle fibers or forming new fibers.

Cardiac muscle does not contain satellite cells, therefore has very limited regenerative capacity after damage. Smooth muscle also lacks satellite cells, however smooth muscle cells are capable of mitosis and therefore are capable of repair and regeneration.