Two major embryonic myosin heavy chains are expressed in embryonic chick breast muscle until the first week after hatching. Of these, one is already detected in the 8-day-old embryo. The other appears on day 12. Two putative slow embryonic isoforms represent minor components transiently expressed between days 8 and 12. A neonatal heavy chain is expressed at low concentrations on day 8 and increases with development. It is the only isoform two weeks after hatching, and is ultimately replaced by the fast myosin heavy chain in the adult muscle. © 1988.
Hofmann, S., Düsterhöft, S., & Pette, D. (1988). Six myosin heavy chain isoforms are expressed during chick breast muscle development. FEBS Letters, 238(2), 245–248. https://doi.org/10.1016/0014-5793(88)80488-5