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

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 CaPO4 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...

Source: The Anatomical Record Part B: The New Anatomist - January 18, 2018 Category: Anatomy Authors: Ugo E. Pazzaglia, Marcella Reguzzoni, Francesca Pagani, Valeria Sibilia, Terenzio Congiu, Andrea G. Salvi, Anna Benetti Tags: Full Length Article Source Type: research