Study of Endochondral Ossification in Human Fetalcartilage Anlagen of Metacarpals: Comparative Morphology of Mineral Deposition in Cartilage and in the Periosteal Bone Matrix

Abstract

The progression of mineral phase deposition in hypertrophic cartilage and periosteal bone matrix was studied in human metacarpals primary ossification centers before vascular invasion began. This study aimed to provide a morphologic/morphometric comparative analysis of the calcification process in cartilage and periosteal osteoid used as models of endochondral ossification. Thin, sequential sections from the same paraffin inclusions of metacarpal anlagen (gestational age between the 20th and 22nd weeks) were examined with light microscopy and scanning electron microscopy, either stained or heat-deproteinated. This process enabled the analysis of corresponding fields using the different methods. From the initial CaPO nucleation in cartilage matrix, calcification progressed increasing the size of focal, globular, randomly distributed deposits (size range 0.5-5 µm), followed by aggregation into polycyclic clusters and finally forming a dense, compact mass of calcified cartilage. At the same time, the early osteoid calcification was characterized by a fine granular pattern (size range 0.1-0.5 µm), which was soon compacted in the layer of the first periosteal lamella. Scanning electron microscopy of heat-deproteinated sections revealed a rod-like hydroxyapatite crystallite pattern, with only size differences between the early globular deposits of the two calcifying matrices. The morphology of the early calcium deposits was similar in both cartilage and osteoid, with variations in size and density only. However, integration of the reported data with the actual hypotheses of the mechanisms of Ca concentration suggested that ion transport was linked to the progression of the chondrocyte maturation cycle (with recall of H O from the matrix) in cartilage, while ions transport was an active process through the cell membrane in osteoid. Other considered factors were the collagen type specificity and the matrix fibrillar texture. Anat Rec, 301:571-580, 2018. © 2017 Wiley Periodicals, Inc.

Osteoconductive Properties of a Volume-Stable Collagen Matrix in Rat Calvaria Defects: A Pilot Study

“…Further support for this suggestion comes from our observations that VSCM favors the formation of a mineralized extracellular matrix, that resembles the hypertrophic cartilagelike tissue of growth plates and ossification centers during development [31] and the fracture callus [32]. We found aggregated small mineralization nodules surrounding the cells that featured completely separated but randomly dispersed spheroidal-shaped cells with a halo.…”

“…The histological analysis identified a heterogeneous pattern of bone formation within the implanted VSCM (Figures 1-4) in eight specimens (A); one specimen had no bone formation penetrating into the VSCM (Figure 5). Highly magnified views demonstrated two types of mineralized tissue formation: (i) the expected new woven bone with the characteristic osteoblast seams and (ii) clusters of a highly scattered mineralized extracellular matrix resembling hypertrophic chondrocytes during development [30,31] and endochondral fracture healing [32] Impressively is the morphology of the mineralizing cells that occasionally form staples, the hallmarks of hypertrophic chondrocytes in the growth plate (C) but are also loosely distributed in their mineralized matrix (D). The strong uptake of the dye produces a dark purple stain that indicated higher mineralization of the extracellular matrix compared to the pink staining of the classical newly formed bone that is produced by the osteoblasts.…”

Morphology of joints and patterns of cartilage calcification in the endoskeleton of the batoid Raja cf. polystigma

“…Despite the large variation in the shape and size of the tesserae, these are observed among species of all the major elasmobranch groups (Dean & Summers, 2006; Maisey et al, 2020; Seidel, Blumer, et al, 2020; Seidel, Jayasankar, et al, 2020) to play in the endoskeleton of these fish the analogous, mechanical function of the bones in the tetrapods. However, no specific attention has been paid to comparing the mineral deposition in cartilaginous fish with that of mammalian endochondral ossification, where calcification has been extensively documented to be associated with chondrocytes transformation, such as hypertrophy (Pazzaglia et al, 2018, 2020). This has left the question of the mechanism of calcium and phosphorus concentration and Ca 2 PO 4 nucleation in the cartilage ECM of elasmobranchs endoskeleton segments unanswered.…”

Iron Deposition in the Growth Plate of Long Bones of the Offspring When Given During Pregnancy in Rat Model

“…It is assumed that the iron deposition seen in the knee synovial membrane would come from blood entering the joint 18 . Besides iron, other mineral deposition in cartilage matrix always occurs before it occurs in bone because it provides the necessary, firm substrate for osteoblasts deposition 19 .…”