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A Compartment Of Tendon Progenitors

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A Somitic Compartment of Tendon Progenitors Summary
Tendons are some of the most important tissues in the body of any organism, transferring the power created by the muscles to the bones and allowing coordinated body movements to occur. However, until recently there was very little known about the origin of this tissue and most of the research performed focused on the limbs and the tendons associated with them. Along with the limited amount of research seemingly none of it was focused on the axial and ventrolateral body wall tendons. It was not until the discovery of Scleraxis (Scx), a bHLH transcription factor found in progenitor cells and mature tendons, that tendons could be observed through the embryonic stages (Schweitzer et al. …show more content…

Upon confirming that axial and intercostal tendons originated from the somites, the researchers wanted to determine if the other somitic compartments affected the syndetome fate. Double whole-mount in situ hybridization was used to compare Scx in progenitor cells, Pax1 in sclerotome, and MyoD in myotome. Scx expression was restricted to the anterior and posterior borders while MyoD expression was present in the center of the myotome with no overlap of the two markers. When Scx was compared to Pax1 it appeared that they existed in the same region; however, Pax1 was expressed more ventromedial and Scx was closer to the myotome, these markers did not have any overlap either. Additionally, Scx expression occurred much later in development compared to MyoD and Pax1(Kiefer and Hauschka, 2001; Stockdale et al., 2000). It showed that the Scx expression progenitor cells had a distinct fate producing a separate compartment of tendon progenitor cells, which did not overlap with the adjacent tissues.
To establish the origin of the syndetome a fate map was created using a chick-quail chimera where two successive sclerotomes or dermomyotomes were transplanted from a quail to a chick embryo.
Utilizing in situ hybridization to visualize Scx expression and QCPN to identify quail cells, sclerotome and Scx expressing tendon

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