Jd. Lillich et al., BIOCHEMICAL, HISTOCHEMICAL, AND IMMUNOHISTOCHEMICAL CHARACTERIZATION OF DISTAL TIBIAL OSTEOCHONDROSIS IN HORSES, American journal of veterinary research, 58(1), 1997, pp. 89-98
Objective-To compare the biochemical, histochemical, and immunohistoch
emical profiles of articular cartilage from horses with naturally acqu
ired distal tibial osteochondrosis (OC) with cartilage from a similar
location in clinically normal horses. Animals-9 affected horses (group
1, 16 OC lesions) and 4 control horses (group 2, 8 normal osteochondr
al specimens). Procedure-OC specimens were collected during arthroscop
ic removal of the fragment, and control specimens were collected by as
eptic osteotomy. Uronic acid, total protein, total glycosaminoglycan (
GAG), chondroitin sulfate (CS), and keratan sulfate (KS) contents were
determined. Histomorphologic, histochemical, and immunohistochemical
examinations were performed on specimens after snap freezing at -80 C
and cryosectioning. Monoclonal antibodies (MAB) 3B3 and 5D4 were appli
ed for location of epitopes of CS and KS, respectively. Results-OC les
ions had significantly lower quantity of uronic acid, total GAG, and C
S, compared with normal cartilage. OC cartilage had significantly less
intense staining with toluidine blue, along with irregular cellularit
y and tidemark characteristics, compared with normal cartilage. Monocl
onal antibodies 3B3 and 5D4 stained OC cartilage, whereas MAB 5D4 did
not stain control cartilage. Additionally, MAB 3B3 and 5D4 stained the
fibrous tissue that was found firmly attached to the OC lesion locate
d between the parent distal portion of the tibia and OC fragment. Conc
lusion-OC cartilage lesions of the distal intermediate ridge of the ti
bia in horses are biochemically, histochemically, and immunohistochemi
cally distinct from normal cartilage from the same location. Results m
ay reflect the inability of the chondrocyte of the developing joint to
alter matrix components that would allow proper maturation and differ
entiation into bone.