We invite submissions to the PeerJ Collection "[The Biology of Sesamoid Tissues in Vertebrates](https://peerj.com/collections/63-sesamoidbiology/)" to stimulate further research in sesamoid biology: to promote current topics in the field; to disseminate levels of understanding about sesamoid biology; and to move toward an improved synthesis of sesamoids. We encourage all authors to emphasize the latter point, in particular: how do their focused studies relate to the bigger picture of what sesamoids do? We intend to be inclusive of career level, geography and topics of sesamoid biology to maximize the diversity of contributions. We encourage all authors to use preprints to improve dissemination and early feedback.
[Professor Virginia Abdala](https://peerj.com/Virgisara/) Instituto de Biodiversidad Neotropical, UNT-CONICET
[Professor John R. Hutchinson](https://peerj.com/jrhutch/) The Royal Veterinary College, University of London
Skills & Experience
From anatomy and function to genetics and evolution: an improved synthesis of sesamoids
Sesamoid tissues in vertebrate animals are found in tendons or ligaments near joints, and can be mineralized or formed of softer connective tissues. Key examples of these include the patella (“kneecap”), sesamoids in digital flexor tendons of many vertebrates, and sesamoids in jaw joints or vertebral tendons/ligaments of varying species. Sesamoids tend to exhibit traits that are somewhat unusual for connective tissues, such as higher than expected variability and extreme responsiveness to mechanical environment (e.g. ossification during ontogeny dependent on loading regime). These leads to the speculation that they can become “genetically assimilated” during evolution; i.e. begin as phenotypically plastic tissues and then become fixed as their function becomes more selectively advantageous in a given environment. However, there is far more to sesamoids than just this evolutionary scenario. The vast diversity of forms, locations, development, presumptive functions and more that sesamoids take in vertebrate species prompt many exciting questions about what sesamoids do for organisms.