Long bone human anlage longitudinal and circumferential growth in the fetal period and comparison with the growth plate cartilage of the postnatal age

Abstract

The patterns of longitudinal and peripheral growth were analyzed in human autopod cartilage anlagen (fetal developmental stage 20th–22nd week) through morphometric assessment of chondrocyte parameter size, shape, alignment and orientation between peripheral and central sectors of the anlage transition zone defined by primary ossification center and the epiphyseal basis. The aim was to correlate the chondrocyte dynamics with the longitudinal and peripheral growth. A further comparison was carried out between the corresponding sectors of the postnatal (3–5 months old) growth plate cartilage documenting: (1) the different chondrocyte framework and the new peripheral mechanism; (2) the opposite direction of fetal periosteal ossification versus the Lacroix bone bark. Measurement of multiple parameters (% lac area, % total matrix area, total lac density and mean single lac area), which characterize the cartilage Anlage growth, suggested the following correlations with chondrocyte duplication rate: (a) slow duplication rate ≈ coupled, intralacunar chondrocytes (in central epiphysis); (b) repeated/frequent cell duplications ≈ clusters (in the basal epiphyseal layer); (c) clusters of chondrocytes before becoming hypertrophic were stacked up on the top of each other (both in the Anlage transition zone or in the columns of metaphyseal growth plate); (d) enhanced osteoclastic resorption of the Lacroix bone bark lower end, extended to the more external metaphyseal trabeculae counterbalancing the discrepancy between the epiphyseal and the diaphyseal circumferential growth.

Discovery of CTSK+ Periosteal Stem Cells Mediating Bone Repair in Orbital Reconstruction

“…22 The main function of the periosteum is to maintain cortical bone homeostasis and supply cortical bone nutrition. 23 , 24 When a bone defect occurs, the precursor cells in the periosteum divide, migrate, and undergo osteogenic differentiation. 41 – 43 This also indicates that CTSK + PSCs are more in line with the cell characteristics required for intramembranous osteogenesis.…”

“…22 Periosteum is mainly responsible for the formation of the cortical bone. 23 , 24 The osteogenic ability mainly depends on the highly heterogeneous cells with multidirectional differentiation ability in the germinal layer. 25 , 26 Using lineage tracing technology, researchers found Nestin + , 27 Sox9 + , 28 , 29 Mx1 + αSMA + , 30 , 31 and other osteogenic cell lineages in the periosteum.…”

The combined cartilage growth – calcification patterns in the wing‐fins of Rajidae (Chondrichthyes): A divergent model from endochondral ossification of tetrapods

“…This structural layout is combined with increased chondrocyte volume (hypertrophy) and mineral deposition in the inter‐columnar cartilage. The latter forms the substratum for osteoblasts apposition, followed by remodeling of the mixed cartilage/osteoid calcified tissue (Pazzaglia et al, 2019 ; 2020 ). With the due differences, in Rajidae wing‐fin radials, longitudinal rows of chondrocytes have been observed in the cylindrical tiles, and the same pattern (but with a radial layout) is also present in the polygonal tesserae of the elasmobranchs crustal calcification (Maisey et al, 2020 ; Seidel et al, 2016 , 2017 ).…”

A multiomic atlas of human early skeletal development

“…In the appendicular skeleton, the nascent synovial joint first appears as an interzone condensation in the limb bud at 5-6 PCW 3 , which subsequently forms a cavitated region that articulates adjacent incipient cartilage templates. The latter acts as a temporary scaffold to facilitate development of the body plane and is gradually replaced by bone tissue as development proceeds through endochondral (EC) ossification 4,5 .…”