Fig. 7

Epitendon cellularity in flexor digitorum tendons scored using a Bonar scoring system. a Cellularity score for distal epitendon regions of flexor digitorum tendons. Higher epitendon cellularity was observed in distal regions of flexor digitorum tendons of 10-wk HRHF animals, compared to FRC rats (*: p < 0.05). The remaining groups showed no significant (ns) differences in distal epitendon cellularity, compared to FRC rats. b Cellularity score for intramuscular epitendons of flexor digitorum tendons, showing no group differences. a&b For each, the mean + 95% CI is shown for: FRC rats (n = 10), TR-then-TM (n = 10 reach limbs), and 10-wk HRHF rats (n = 13 reach limbs) and 10-wk HRHF+TM rats (n = 8 reach limbs). c-e Representative images of distal flexor digitorum tendons (T) in a FRC rat (c), 10-wk HRHF rat (d) and 10-wk HRHF+TM rat (e). TR-then-TM rats had similar histological findings as FRC rats (see panel a); therefore, a representative image is not included. Some of this higher cellularity in 10-wk HRHF rats’ epitendons was due to an elevated presence of CD68+ macrophages (f and inset). Note that there are many CD68+ macrophages in the endotendon and surrounding connective tissues (ct) in the 10-wk HRHF rat image shown. This was not a typical finding in the other groups (images not shown). Scale bar = 50 μm