On the presence of the patella in frogs

ABDALA VIRGINIA; MIRIAM CORINA VERA; PONSSA MARIA LAURA

The Anatomical Record

Wiley

Año: 2017 vol. 3000 p. 1747 - 1755

The patella is one of the most studied sesamoids. Historically, the patella is described as a big sesamoid embedded in the tendon of the quadriceps femoris muscle. This sesamoid is studied from developmental,functional, clinical and anatomical perspectives. The presence of a patella is reported in squamatans, birds and mammals. Lissamphibians are identified as the major lineage that fail to develop a patella. However, thissesamoid is reported at least once in anurans, but without detailed anatomical discussions. Through anatomical and histological studies we examined the topography and tissue composition of two structures that we identify asthe proximal and distal patellae in several anuran species. We explored the evolution of these sesamoids through ancestral state reconstruction, finding that they are ancestral for amphibians and possibly tetrapods as a whole.The presence of these patellae in anurans would roll back their origin to the last common ancestor of tetrapods. From a functional perspective, the overwhelming evidence of fibrocartilage as a clear response to compressionsuggests that the fibrocartilaginous patellae could also withstand the mechanical stress generated on the knee undergoing compression during limb extension.