Development of human limb muscles based on whole-mount immunostaining and the links between ontogeny and evolution
Etude du développement des muscles des membres humains, basée sur des immuno-marquages in toto et des liens entre ontogenèse et évolution
Résumé
We provide the first detailed ontogenetic analysis of human limb muscles using
whole-mount immunostaining. We compare our observations with the few earlier
studies that have focused on the development of these muscles, and with data
available on limb evolution, variations and pathologies. Our study confirms the
transient presence of several atavistic muscles - present in our ancestors but
normally absent from the adult human - during normal embryonic human development,
and reveals the existence of others not previously described in human embryos.
These atavistic muscles are found both as rare variations in the adult population
and as anomalies in human congenital malformations, reinforcing the idea that
such variations/anomalies can be related to delayed or arrested development. We
further show that there is a striking difference in the developmental order of
muscle appearance in the upper versus lower limbs, reinforcing the idea that the
similarity between various distal upper versus lower limb muscles of tetrapod
adults may be derived.