Development and ageing of the articular cartilage of the rabbit knee joint: distribution of the fibrillar collagens

Abstract

The development of the articular cartilage of the rabbit knee joint from the 17-day fetus to the 2-year adult rabbit has been examined. At 17 days, the developing femur and tibia are separated by the interzone. Cavitation occurs around 25 days; the cells of the intermediate layer flatten and move onto those of the chondogenous layers to create the articular surfaces. After birth, growth of the cartilage is mainly the result of matrix production. Ossification of the epiphyses is complete by 6 weeks postpartum. Horizontal zones can be distinguished in the articular cartilage; the superficial cells are aligned parallel to the surface, but in the deep layers the cells are in columns. The tidemark is first seen at 12-14 weeks. The matrix of the interzone in the 17-day fetus contains types I, III and V collagens, but no type II. After cavitation at 25 days, the surface layer of the articular cartilage still contains type I, but no type II collagen. From 6 weeks postnatal onwards, type II collagen is present throughout the cartilage and type I disappears. Type III collagen is initially in the inter-territorial matrix, but later it is mainly pericellular. Type V collagen is pericellular both in the chondrogenous layers and later in the articular cartilage, but is not present in the epiphyseal cartilage below. From 6 weeks onwards, types III and V collagens create a capsule around all the chondrocytes above the tidemark. The relationship of types V and XI collagens is discussed. It is concluded that the articular chondrocytes form a unique subset of cells from the earliest stages of joint formation in the fetal rabbit.

Typ 5-Kollagen im Gelenkknorpel von Mensch und Pferd

“…The identification of type V collagen in the matrix around the putative chondrocytes in the chondrogenous layers of developing joints Ashhurst 1996 and2001) showed that these cells are unique and distinct from the chondrocytes of epiphyseal cartilage. Since that time further distinctive features have emerged.…”

“…This antibody was affinity purified. Its primary reactivity is against the α2 chain of type V collagen, but it shows low reactivity against the α2 chain of type XI collagen (Bland and Ashhurst 1996).…”

“…The immunohistochemical procedure used was described in detail by Bland and Ashhurst (1996). Briefly, the sections were pretreated with trypsin, hyaluronidase , l-lysine, and undiluted heat-inactivated normal rabbit serum.…”

“…A striking feature of the fetal rabbit knee joint before cavitation is the pericellular distribution of type V collagen in the matrix of the chondrogenous layers; there is none in the underlying epiphyseal cartilage. The pericellular distribution of type V collagen around articular chondrocytes persists throughout life in the rabbit Ashhurst 1996 and2001). Other unique features of articular cartilage are that the matrix does not contain type II collagen until after cavitation and matrilin-1 is never found in normal articular cartilage; both are present in epiphyseal cartilage (Bland and Ashhurst 1996and 2001, Kavanagh and Ashhurst 1999, Murphy et al 1999, Segat et al 2000, Hyde et al 2007).…”

Postnatal development of depth-dependent collagen density in ovine articular cartilage

“…Both the predominant orientation in the collagen network and the amount of collagen in the network affect the mechanical behaviour, and thus the functioning, of AC [15-18]. The collagen network remodels between birth and maturity: the adult depth-dependent structure is absent at birth [19-23], collagen type I is replaced by collagen type II [24-26], and collagen densities increase [27-29] with depth-dependent variation [21]. …”