Japanese Journal of Veterinary Research;Volume 21, Number 1-2

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HISTOLOGICAL STUDIES IN THE INSERTION OF THE TENDON ON THE DISTAL PHALANX OF THE HORSE

OTOMO, Kanjuro

Permalink : http://hdl.handle.net/2115/2012
JaLCDOI : 10.14943/jjvr.21.1-2.1

Abstract

Development and age-change occurring in the insertion of the extensor tendon and the deep flexor tendon on the distal phalanx were studied on the histological level in horses varying in age from embryo (18 cases) to adult (53 cases). Moreover, the fine structure of the insertion of the deep flexor tendon was partly observed. The five following developmental stages were distinguished according to the histological changes in the insertion of the extensor tendon : 1) The stage of cartilage (from 15 to 80 cm embryos); 2) The stage of spongy bone formation (from 85cm embryos to 2 weeks old infants); 3) The stage of fibrous bone formation (from 3 months to 1.5 years old); 4) The stage of lamellar bone formation (from 1.5 to 3 years old); and 5) The stage of completion of the insertion (4 years old and over). The five following developmental stages were distinguished according to the histological changes in the insertion of the deep flexor tendon : 1) The stage of cartilage (from 15 to 80 cm embryos); 2) The stage of inner compact layer formation (from 85cm embryos to 2 weeks old infants); 3) The stage of outer compact layer formation (from 3 months to 1.5 years old); 4) The stage of fibrocartilage formation (from 1.5 to 3 years old); and 5) The stage of completion of the insertion (4 years old and over). Electron microscopic observation in the insertion of the deep flexor tendon can be described as follows. Tendons were arranged perpendicular or oblique to the bone surface and entered the bone in an approximately perpendicular or oblique position. In the tendon, the axial period of collagenous fiber was on the average 640 Å. It was divided into D-region (high dense region) and L-region (comparatively low dense region); the width of D-region was on the average 380 Å, and that of the L-region about 260 Å, respectively determined by measurements on several fibrils. Eleven dark transverse lines per period can usually be observed, 8 in the D-region and 3 in the L-region. The diameter of collagenous fiber measured about 3,000 Å and maximum was about 4,000 Å. In the bone, the axial period of the collagenous fiber was from 600 to 700 Å. It was divided into D-region and L-region, and several dark transverse lines per period can usually be observed. The diameter of the fibers measured about 1,000 Å.

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