Scanning electron microscopy study of bone intracortical vessels using an injection and fractured surfaces technique

Abstract

The intracortical canal/vessel systems of long bones are not yet completely understood in terms of their morphology and physiology, mainly because of the difficulty of injecting the small calibre vessels and cutting the calcified matrix. Here, we apply a novel method combining perfusion of the vessels and fracture of the cortical bone to enlighten the architecture of this system. The femurs of ten rabbits were perfused with a water-soluble dye (China ink) or alcoholic glycerol solution, and the fractured cortex specimens were then examined by scanning electron microscopy (SEM). The results document: (1) the fibrillar structure of the canal surfaces; (2) the perivascular environment with cellular components in different phases of incorporation within the bone matrix; (3) previously unreported filamentous structures on the outer surface of vessels, which could be interpreted as non-myelinic nerve fibres; (4) the inner organisation of the cutting cones. Although based exclusively on morphology, these observation have some relevance to increasing knowledge of bone circulation physiology in the cortical bone.

The Sealed Osteons of Cortical Diaphyseal Bone. Early Observations Revisited With Scanning Electron Microscopy

“…The intracortical circulation has been proved to be a dynamically regulated system whose flows are controlled from the outside (Stein et al,1958; Michelsen,1967; Gross et al,1979; Brinker et al,1990) and these data fit with morphological observations that the network, with the exclusion of the cutting cones loop, is made of capillaries made of the basal membrane and endothelial cell layer (Pazzaglia et al,2010b). Changes in flow dynamics in the system may cause some branches to become excluded from blood flow, with subsequent collapse and degeneration of the capillary vessel.…”

A model of osteoblast–osteocyte kinetics in the development of secondary osteons in rabbits

“…10 Scheme of the cutting cone geometry showing the internal relationship of the vascular loop with the distribution of the different cell types. The scheme was drawn from images obtained with the SEM fractured cortex technique (Pazzaglia et al, 2010b). Once the recruited osteoblasts have started matrix apposition, their position on the canal surface is set and the only displacement of the cell can be along radial vectors directed toward the central vessel.…”

Atomic Layer Deposition of a Silver Nanolayer on Advanced Titanium Orthopedic Implants Inhibits Bacterial Colonization and Supports Vascularized de Novo Bone Ingrowth

“…These unique observations on SEM of vascular casts of tibial samples show robust new capillary formation by 2 weeks postimplantation, particularly around the struts of the scaffolds, with numerous small caliber vessels emerging from the surrounding periosteum and forming irregular interconnected networks. The presence of numerous highly branched capillaries emerging from pre‐existing vessels is a well‐recognized process in the cortical bone regeneration process, however, we are unaware of their demonstration in the context of solid (particularly titanium) implants. These capillary networks precede mature bone ingrowth into the scaffolds at 2 weeks and are most likely associated with the significant increase in gene expression associated with implantation of roughened titanium surfaces …”

“…Porous scaffolds with roughened surfaces (similar to both Ti‐only and Ti/Ag implants described in our study) provide morphology similar to trabecular bone, to which osteoblasts can attach in vitro and in vivo, differentiate and deposit matrix that will eventually mineralize and begin the formation of woven bone . By 12 weeks' postimplantation, there is clear evidence of bone and vascular remodeling within the porous structure of Ti‐only and Ti/Ag scaffolds, including Volkmann's canals with attendant capillaries—features that are characteristic of mature bone growth . In addition, 2D light microscopic examination of thick histological sections and 3D X‐ray computed microtomographic reconstructions revealed excellent bone ingrowth in both Ti‐only and Ti/Ag scaffolds, similar to that described for rats implanted with titanium coated with either silver‐oxide‐doped hydroxyapatite or silver‐impregnated nanotubes …”