An immunocytochemical study of type I muscle fibres in developing human skeletal muscles.
An immunocytochemical study was done on the skeletal muscles of human fetuses (19-36 weeks gestation), infants and adults using a new monoclonal antibody (McAb) ALD-47. The antibody was generated against slow myosin of chicken and is specific for myosin heavy chain (MHC). In human infants and adults the type I muscle fibres are strongly reactive with this McAb and the type II fibres uniformly non-reactive. In the fetuses from 19-20 weeks gestation (in whom the fibre types are not distinguishable by the histochemical myosin ATPase test) a proportion of muscle fibres react specifically with ALD-47. Other muscle fibres at this stage react positively with a fast specific MHC McAb HM-1.2 or are negative to both ALD-47 and HM-1.2 antibodies. These McAbs, thus, identify three distinct fibre populations in the early fetal muscle which by histochemical staining appears homogeneous. The percentage of ALD-47 positive fibres increases in fetuses at later gestational periods; at all stages these fibres lack reactivity with the HM-1.2 antibody. Because of its selective fibre type reactivity in differentiating muscles, the McAb ALD-47 in conjunction with HM-1.2 should be useful in immunoaffinity fractionation and biochemical studies of myosin isoforms in developing human muscles.
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000911:Antibodies, Monoclonal; D000939:Epitopes; D005455:Fluorescent Antibody Technique; D005865:Gestational Age; D006651:Histocytochemistry; D006801:Humans; D009132:Muscles / Q000196:embryology / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D000939:Epitopes; D010446:Peptide Fragments; D000251:Adenosine Triphosphatases; D009218:Myosins