Ical properties of ligaments rely largely on the collagen and elastic fibres. We found that each the ACL and LT exhibit comparable expression levels of collagen and elastic fibre genes. In fact, for all those collagens which are much more characteristic of ligaments, including collagen varieties I, III and V, expression levels were higher in the ACL and LT compared with all the IL. As mechanical loading is an essential issue modulating gene expression in connective tissues (Murchison et al. 2007; Scott et al. 2011), these findings could recommend that the LT is subjected2013 Anatomical Societyto Compound 48/80 References specialised biomechanical demands and is not just an embryonic vestige that functions as a passive blood vessel bearer. Our interpretation is constant with previous clinical and in vitro biomechanical research (Wenger et al. 2007; Bardakos Villar, 2009; Cerezal et al. 2010). We analysed a panel of small leucine-rich PGs (SLRPs), like Decorin, Biglycan and Fibromodulin, that are crucial ECM components with key functions in the formation and homeostasis of ligaments. These PGs contain collagen- and growth factor-binding molecules which might be involved in the modulation of collagen fibrillogenesis, cell shape, cell development and cell signalling (Corsi et al. 2002; Ferdous et al. 2007, 2010; Kilts et al. 2009). Additionally, it can be properly recognised that PGs favour tissue hydration, acting as a lubricant involving collagen fibres. They are also essential for the viscoelastic properties that enable ligaments beneath tension to IL-16 Proteins Formulation return to their original shapes once the tension is removed (Scott, 1988; Weiss et al. 2002). Our findings showed that the ACL has the highest levels of Decorin (the predominant PG in ligaments) and Fibromodulin, which may perhaps account for the stiffness on the ligament. Constant with this interpretation, the ACL is stiffer than the LT. Accordingly, animal models lacking these PGs show a disorganisation from the collagen fibres accompanied by decreased ligament stiffness. In these models, the ACL seems hypertrophied and torn, and it might exhibit ectopic ossification (Gill et al. 2002; Zhang et al. 2006; Kilts et al. 2009). The LT showed substantially greater levels of Biglycan expression than the IL or ACL. Similar to Decorin, Biglycan is actually a proteodermatan sulphate SLRP that mediates ligament stiffness (Kilts et al. 2009), and it may compensate to get a deficiency of Decorin (Corsi et al. 2002; Zhang et al. 2006). Hence, despite these compositional differences in SLRPs, the mechanofunctional properties from the ACL and LT can be similar to each other and as a result distinct from those from the IL. Proteoglycans modulate the bioavailability of development factors. Therefore, the higher expression levels of PGs in the LT and ACL correlate using the elevated expression of TGFb1 identified in these ligaments. Decorin, Biglycan and Fibromodulin all bind TGFb1, and they modulate its function in association with enzymatic processing (Hausser et al. 1994; Hildebrand et al. 1994). TGFb1 has been involved in ligament development, homeostasis and healing, in turn regulating fibroblast differentiation, proliferation, adhesion and migration; moreover, it promotes ECM synthesis and inhibits enzymatic degradation (Peltonen et al. 1991; Ghahary et al. 1993; Mauviel, 1993; Scherping et al. 1997; Uria et al. 1998; Evans, 1999; Lorda-Diez et al. 2009; Ferdous et al. 2010; Achari et al. 2011; Wang et al. 2011a). TGFb1 also promotes collagen cross-linking, thereby contributing to ligament stiffness (Ele.