Flexor tendon blood vessels

The aim of this study was to assess rabbit long flexor tendon vascularity i n a qualitative and quantitative manner using immunohistochemistry. The end othelial cell surface marker CD31 was targeted with a specific monoclonal m ouse-anti-human antibody with good species cross-reactivity. Subsequent sig nal amplification and chromogen labelling allowed vessel visualization. Com puter image analysis was performed. Values for vessel number and total vess el area per section, as well as the sections' cross-sectional tendon areas, were obtained. There was a consistent deep tendon avascular zone between the A2 and A4 pul ley in the rabbit forepaw. This was not the case in the hindpaw, with dorsa lly orientated longitudinal vessels coursing the length of the intrasynovia l tendon. The area of least vascularity in the hindpaw was around the metac arpophalangeal joint. We therefore recommend the use of hindpaw tendons whe n using the rabbit as a flexor tendon experimental model. This is because i ts vascular pattern is similar to that of the human flexor digitorum profun dus.