“…The most detailed results have been obtained in birds (Bandman et al, 1982;Crow and Stockdale, 1986;Miller and Stockdale, 1986; for reviews, see Stockdale and Miller, 1987, and Stockdale, 1990), in small mammals, such as mice (Rubinstein and Kelly, 1981;Whalen et al, 1981;Lyons et al 1983;Vivarelli et al, 1988) and cats (Hoh and Hughes, 1989). Studies have also been made on the human fetus (Pons et al, 1986;Draeger et al, 1987 39,53,64,84,98,122,143,180,224 Pons et al (1986). We used 4 monoclonal antibodies (MAb) raised against different types of human myosin heavy chains: a p type (slow) myosin from the heart ventricle of an adult (antibody A), a fast myosin immunopurified from the quadriceps muscle of an adult (antibody B), a myosin from a 22-wk-old fetus (antibody C) and a myosin from adult atrium (antibody D).…”