Microvascular features and ossification process in the femoral head of growing rats

Abstract

In the epiphysis of long bones, different patterns of development of ossification processes have been described in different species. The development of the vascularisation of the femoral head has not yet been fully clarified, although its role in the ossification process is obvious. Our aim was to investigate ossification and vascular proliferation and their relationship, in growing rat femoral heads. Male Wistar rats aged " 1, 5 and 8 wk and 4, 8 and 12 mo were used. Light microscopy frontal sections and vascular corrosion casts observed by scanning electron microscopy were employed. In the rat proximal femoral epiphysis, ossification develops from the medullary circulation of the diaphysis, quickly extending to the neck and the base of the head. Hypertrophic chondrocytes occupy the epiphyseal cartilage, and a physeal plate with regular cell columns is present. Starting from about the end of the third month one or more points of fibrovascular outgrowth, above the physeal line, can be observed in each sample. They are often placed centrally or, sometimes, peripherally. The fibrovascular outgrowths penetrate deeply into the cartilage and extend laterally. At age 8 mo, large fibro-osseous peduncles connect the epiphysis to the diaphyseal tissue. At 12 mo, the entire epiphysis appears calcified with an almost total absence of residual cartilage islands. This situation differs in man and in other mammals due both to differing thickness of the cartilage and to the presence of more extensive sources of blood vessels other than the diaphyseal microcirculation, as supplied by the teres ligament and Hunter's circle. In young rats, subchondral vessels and the synovial fluid could play a role in feeding the ossifying cartilage. Later, a loss of resistance of the physis due to marked degeneration of the cell columns, and extensive chondrocyte hypertrophy permit fibrovascular penetration starting from diaphyseal vessels rather than neighbouring vascular territories, such as those of the periosteum and capsule.

Ossification of the mouse metatarsal: Differentiation and proliferation in the presence/absence of a defined growth plate

“…By contrast, mouse epiphyseal cells undergo unified hypertrophy across the direct epiphysis and they do so prior to the complete obliteration of the small columnar zone chondrocytes and invasion by the primary center. This interspecific difference may be due to the lack of cartilage canals in the mouse (Floyd et al, 1987;Morini et al, 1999Morini et al, , 2004 and therefore may be an indirect body size phenomenon. Mouse chondrocytes depend on peripheral diffusion from the perichondrium for their nutritive supply (Maes et al, 2004), and once the metatarsal epiphysis becomes sufficiently large, the resultant hypoxia may induce factors (Schipani et al, 2001) that promote hypertrophy and invasion by the primary center of ossification.…”

Simultaneous 3D visualization and quantification of murine bone and bone vasculature using micro‐computed tomography and vascular replica

“…The surrounding tissue and bone is then removed (corroded) and the resulting replica is dried, rendered conductive, and examined using SEM (Hodde and Nowell, 1980;Northover et al, 1980). In particular, VCC combined with SEM was applied for the study of the vasculature and the microvasculature of bones primarily in rats (Aharinejad et al, 1995;Hirano et al, 1996;Morini et al, 1999Morini et al, , 2006Okada et al, 2002;Pannarale et al, 1997;Stanka et al, 1991). While vascular corrosion casts represent the 3D architecture of the vascular network, SEM can only provide two-dimensional (2D) data.…”

Perlecan Immunolocalizes to Perichondrial Vessels and Canals in Human Fetal Cartilaginous Primordia in Early Vascular and Matrix Remodeling Events Associated with Diarthrodial Joint Development

“…Intrachondral vascularization events have previously been investigated in the talus of the human foot (Cheng et al 1997), human femoral head (Trueta 1957;Skawina et al 1994), fetal elbow (Reidenbach and Schmidt 1994), femoral head and tibiae of growing rats (Kai et al 1992;Hirano et al 1994;Morini et al 1999;Davoli et al 2001;Lee et al 2001) and mice (Cole and Wezeman 1985;Floyd et al 1987) newborn and postnatal rabbit knee (Ganey et al 1992;Shapiro 1998;Doschak et al 2003), and in normal and arthritic human synovial tissue (Haywood and Walsh 2001).…”