Myofibroblasts in the accessory ligament (distal check ligament) and the deep digital flexor tendon of foals.
OBJECTIVE
To demonstrate myofibroblasts in the accessory ligament of the deep digital flexor tendon (ie, distal check ligament) and deep digital flexor tendon of clinically normal foals.


METHODS
Tissue specimens from 25 foals that were necropsied for reasons unrelated to this study and unrelated to musculoskeletal disease.


METHODS
The distal check ligament and deep digital flexor tendon of both forelimbs were examined histologically. Myofibroblasts were identified by immunohistochemical staining specific for alpha-smooth muscle actin (alpha-SMA).


RESULTS
Most of the cells in the distal check ligament and deep digital flexor tendon of all foals stained positive for alpha-SMA.


CONCLUSIONS
Myofibroblasts made up most of the cells in the distal check ligament and deep digital flexor tendon of clinically normal foals. These cells have contractile ability and therefore, may play a role in flexure contracture of these tendons. The ability of tetracycline to chelate calcium or decrease the expression of the contractile protein alpha-smooth muscle actin could inhibit the myofibroblasts' ability to contract, thus providing a rationale for tetracycline administration as a treatment of distal interphalangeal joint flexor deformity in foals.
Hartzel
D K
DK
Laboratory for Comparative Orthopaedic Research, College of Veterinary Medicine, Michigan State University, East Lansing 48824, USA.
Arnoczky
S P
SP
Kilfoyle
S J
SJ
Stick
J A
JA
D000199:Actins / Q000378:metabolism; D000818:Animals; D003094:Collagen / Q000378:metabolism; D005260:Female; D005347:Fibroblasts / Q000166:cytology; D005552:Forelimb / Q000002:abnormalities / Q000033:anatomy & histology; D006736:Horses / Q000033:anatomy & histology*; D007150:Immunohistochemistry / Q000662:veterinary; D008023:Ligaments, Articular / Q000166:cytology*; D008297:Male; D018482:Muscle, Skeletal / Q000166:cytology; D013710:Tendons / Q000166:cytology*
D000199:Actins; D003094:Collagen