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Animal Models of Osteonecrosis
Published in Yuehuei H. An, Richard J. Friedman, Animal Models in Orthopaedic Research, 2020
Kensaku Masuhara, Minoru Matui, Katsuya Nakata, Keiro Ono
Homogeneous distribution of blood vessels in the epiphysis was observed in the femoral heads with normal ossification and in heads with completely repaired ON (Stage 3), while absence of blood vessels throughout the epiphysis was demonstrated in the femoral heads with fresh ON without repaired tissue (Stage 1) and in the femoral heads in which no ossification had occurred at all. These findings suggest that ON and disturbed ossification may be the result of the same pathogenetic process.
The skeleton and muscles
Published in Frank J. Dye, Human Life Before Birth, 2019
The initiation of intramembranous ossification occurs when specific mesenchymal cells called osteoblasts begin to secrete a specific extracellular matrix. This matrix, together with an enzyme, alkaline phosphatase, causes deposits of calcium phosphate crystals to form, resulting in the formation of bone.
Skeletal Embryology and Limb Growth
Published in Manoj Ramachandran, Tom Nunn, Basic Orthopaedic Sciences, 2018
Rick Brown, Anish Sanghrajka, Deborah Eastwood
Mesenchymal cells condense and proliferate, with cells developing into chondroblasts (chondrification). A cartilaginous extracellular matrix is laid down (anlage) forming the template for bone formation. The matrix is resorbed, and osteoblasts brought into the area by newly formed capillary networks begin ossification. This process begins within the centre of the diaphysis (primary ossification centre), and proceeds outward from the medullary cavity and inward from the periosteum. This sequence of events then occurs at the epiphyseal centres of ossification.
Auditory rehabilitation after temporal bone fracture with cochlear implants – a case control study
Published in Cochlear Implants International, 2023
Katharina Heine, Max Eike Timm, Lutz Gärtner, Thomas Lenarz, Anke Lesinski-Schiedat
The surgical technique is largely standardised containing a routine mastoidectomy and posterior tympanotomy as performed in every case (Lenarz et al., 2013) When it comes to insertion of the electrode it is of paramount importance to achieve sufficient cochlear coverage to potentially stimulate all remaining spiral ganglion cells (Lenarz, 2017). Complete insertion of electrodes may be hindered by obliteration of the cochlea due to connective tissue or bone, which may develop after temporal bone fracture. Depending on the degree of cochlear obliteration, also determined intraoperatively by the surgeon, different approaches to the basal turn of the cochlea were performed. The various surgical techniques suitable for varying degrees of ossification are described by Lenarz (2017). Usually, if fibrous obliteration occurred, it was possible to remove the obliterating tissue. In case of increased obliteration, the standard procedure of inserting through the round window can be reached by using the drill-out technique (Balkany et al., 1998). However, none of our cases required the classic drill-out procedure. In the two cases of complete obliteration of the apical turn implantation of the double-array electrode was necessary. Based on the operating protocols patients with any fibrous tissue inside the opened cochlea were classified as positive for obliteration.
Epidermal growth factor signalling pathway in endochondral ossification: an evidence-based narrative review
Published in Annals of Medicine, 2022
L. Mangiavini, G. M. Peretti, B. Canciani, N. Maffulli
Bones form through two complex processes: intramembranous or endochondral ossification. During the former, mesenchymal cells directly differentiate in osteoblasts by activating the RUNX-2 pathway. This process occurs in most of the calvarial bones and in the clavicle [1]. Endochondral ossification is more complex, and it involves an initial cartilage anlage, which is then replaced by bone [1]. Mesenchymal progenitors first condensate and then start differentiating into chondrocytes. These latter cells pile up in columns, exit the cell cycle, and secrete an osteogenic matrix and pro-angiogenic factors, such as Vascular Endothelial Growth Factor (VEGF) [2,3]. Subsequently, perichondrial cells surrounding the primary cartilage anlage invade the template together with blood vessels, and they differentiate into osteoblasts, forming the primary ossification centre. Subsequently, chondrocytes form the growth plate at both ends of the primary ossification centre [4].
Impact of intrauterine exposure to the insecticide coragen on the developmental and genetic toxicity in female albino rats
Published in Egyptian Journal of Basic and Applied Sciences, 2022
Amel Ramadan Omar, Ahmed Emam Dakrory, Marwa Mohamed Abdelaal, Heba Bassiony
In the present study, coragen treatment induced fetal growth retardation through fetal body weight and fetal length, morphological disorders including; hematoma and skeletal malformation such as loss of chondrification of some tail vertebrae and shortage of last rib. In the same way, a previous study reported that consumption of coragen by rats had a negative impact on calcium and bone properties, resulting in osteoporosis [28]. This might be related to the delay of ossification and skeletal anomalies in the current study. As well as, teratogenic development was observed in chick embryo upon exposure to chlorantraniliprole [11]. Moreover, increased fetal resorption and a decrease in live fetal number, combined with skeletal anomalies, were recorded as indication of teratogenicity in the exposed pregnant rats to other insecticides such as lufenuron [26], chlorpyrifos [29], cypermethrin [27,30], dimethoate [31], emamectin benzoate [32], fipronil [33] and organophosphorous pesticides [34].