The Role of Mechanobiology in the Attachment of Tendon to Bone - Structural Interfaces and Attachments in Biology - page 231

Fig. 11.5 Blitz et al . suggested the following model for the contribution of both tendons and muscles
to enthesis formation. Through a biphasic process, tendons regulate enthesis initiation and muscles
control its subsequent growth. Further research is necessary to determine the mechanism whereby
muscle contraction regulates enthesis development (reproduced, with permission, from ref. [ 111 ])
tendon cells at their bony insertion site. When BMP-4 expression was blocked in
Scx expressing cells, the enthesis (and associated bone ridges) did not form. This
implicates BMP-4 as a key mediator of tendon-specific signaling for enthesis
formation. The key regulators of endochondral ossification, collagen II, Ihh,
PTHrP, and collagen X were expressed at the developing enthesis.
11.4.1 Development of Structural Gradients in the Enthesis
This section describes the developmental patterns that lead to the complex structure
and composition of the tendon-to-bone insertion. The temporal expression of ECM
molecules was described in detail using in situ hybridization experiments throughout
murine fetal and postnatal development [ 108 ]. At birth, the bone side of the
supraspinatus tendon-to-bone insertion was largely made up of un-mineralized