DEER ANTLER DOES NOT REPRESENT A TYPICAL ENDOCHONDRAL GROWTH SYSTEM -IMMUNOIDENTIFICATION OF COLLAGEN TYPE-X BUT LITTLE COLLAGEN TYPE-II IN GROWING ANTLER TISSUE

The collagen isotypes present at early (6 week) and late (5 month) sta ges of growing deer antler were isolated and identified. Pepsin-digest ed collagens were separated by differential salt fractionation, SDS-PA GE and Western blotting and subsequently identified by immunostaining. Cyanogen bromide digestion of antler tissue was used to establish a c ollagen type-specific pattern of peptides, and these were also identif ied by immunoblotting. Collagen type I was found to be the major colla gen in both early-and late-stage antler. Collagen type II was present in the young antler in small amounts but was not confined to the soft ''cartilaginous'' tip of the antler. Collagen type XI was found in the pepsin digest of the young antler, but collagen type IX was not prese nt at either stage of antler growth. Collagen type X was found in the young antler in all fractions studied. Microscopic study showed that t he deer antler did not possess a discrete growth plate as found in end ochondral bone growth. Unequivocal immunolocalization of the different collagen types in the antler were unsuccessful. These results show th at, despite the presence in the antler of many cartilage collagens, gr owth does not occur through a simple endochondral process. (C) 1997 El sevier Science Inc.