Satellite cells (SC) are quiescent adult muscle stem cells critical for 
postnatal development. Children with cerebral palsy have impaired muscular 
growth and develop contractures. While flow cytometry previously demonstrated a 
reduced SC population, extracellular matrix abnormalities may influence the cell 
isolation methods used, systematically isolating fewer cells from CP muscle and 
creating a biased result. Consequently, the purpose of this study was to use 
immunohistochemistry on serial muscle sections to quantify SC in situ. Serial 
cross-sections from human gracilis muscle biopsies (n = 11) were labeled with 
fluorescent antibodies for Pax7 (SC transcriptional marker), laminin (basal 
lamina), and 4',6-diamidino-2-phenylindole (nuclei). Fluorescence microscopy 
under high magnification was used to identify SC based on labeling and location. 
Mean SC/100 myofibers was reduced by ∼70% (p < 0.001) in children with CP 
(2.89 ± 0.39) compared to TD children (8.77 ± 0.79). Furthermore, SC 
distribution across fields was different (p < 0.05) with increased percentage of 
SC in fields being solitary cells (p < 0.01) in children with CP. Quantification 
of SC number in situ, without any other tissue manipulation confirms children 
with spastic CP have a reduced number. This stem cell loss may, in part, explain 
impaired muscle growth and apparent decreased responsiveness of CP muscle to 
exercise.