IMMUNOHISTOCHEMICAL FINDINGS TYPE-I AND TYPE-II COLLAGEN IN PRENATAL MOUSE MANDIBULAR CONDYLAR CARTILAGE COMPARED WITH THE TIBIAL ANLAGE

In growing animals the mandibular condylar cartilage serves not only a s an articular but also as a growth cartilage, yet, condylar cartilage has some characteristic features that are nor found in growth cartila ge. For example, some reports suggest that type I collagen, which is n ot seen in the growth plate cartilage of long bones, is present in the extracellular matrix of condylar cartilage postnatally. Here, the con dylar and limb bud cartilage of fetal mice was examined. The distribut ion of type I and type II collagen in condylar cartilage was already d ifferent from that in the limb bud at the first appearance of the cart ilage. Type I collagen was demonstrated in the extracellular matrix of the condylar cartilage that first appeared on day 15 of gestation, Ho wever, the reaction for type II collagen was much weaker than that for type I collagen. On day 18 of gestation, type I collagen was still fo und throughout the cell layers but became gradually weaker with depth. Type II collagen was limited exclusively to the deeper layers at this stage. These findings are different from those in the limb bud cartil age, indicating a characteristic feature of the cells in the condylar cartilage present from the prenatal period. (C) 1998 Elsevier Science Ltd. All rights reserved.