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Skeletal Embryology and Limb Growth
Published in Manoj Ramachandran, Tom Nunn, Basic Orthopaedic Sciences, 2018
Rick Brown, Anish Sanghrajka, Deborah Eastwood
During the early stages of development, the embryo has a laminar structure consisting of three different germ cell layers, from which specific systems will develop (Table 3.1). The limb buds first appear at the end of the fourth week of development, with the forelimbs preceding the hindlimbs by 1–2 days. The limb bud consists of a mesenchymal chondrogenic core (from the lateral plate mesoderm) covered by a layer of ectoderm (Figure 3.1).
Formation of the Cranial Base and Craniofacial Joints
Published in D. Dixon Andrew, A.N. Hoyte David, Ronning Olli, Fundamentals of Craniofacial Growth, 2017
In the early part of the 3rd week of human development the third of the primary germ layers, cells of the intraembryonic mesoderm, begin to migrate in both lateral and cranial directions from the midline primitive streak, insinuating themselves between the ectodermal and endodermal layers of the embryonic disc. As the notochord and neural tube form in the midline axis of the embryo, the intraembryonic mesoderm that streams toward the head end of the disc thickens into two well-defined columns of paraxial mesoderm, one on either side of the notochord. More laterally, a thinner intermediate mesodermal band differentiates and beyond it, at the periphery of the embryonic disc, lies an even thinner lateral-plate mesoderm. These mesodermal aggregations are readily seen in cross-sections of the embryonic disc at the end of the 1st month of development. The intermediate mesoderm is significant for its role in the development of the urogenital system, while the cardiovascular and lymphatic systems, as well as the serous membranes that will line the major body cavities, are derivatives of lateral plate mesoderm.
Articular Cartilage Development
Published in Kyriacos A. Athanasiou, Eric M. Darling, Grayson D. DuRaine, Jerry C. Hu, A. Hari Reddi, Articular Cartilage, 2017
Kyriacos A. Athanasiou, Eric M. Darling, Grayson D. DuRaine, Jerry C. Hu, A. Hari Reddi
As in all animals with bilateral symmetry, human embryos develop three germ layers, endoderm, mesoderm, and ectoderm, during embryogenesis. Cartilage and bone are derived from both the mesoderm and ectoderm. The mesoderm, interposed between the ectoderm and endoderm, gives rise to articular cartilage of the long bones. From the mesoderm, the axial skeleton forms from the somites. The somites give rise to muscle, skin, and cartilage, and this process is initiated by its splitting into myotome, dermatome, syndetome, and sclerotome. The lateral plate mesoderm generates the appendicular skeleton (limbs) (Olson et al. 1996), specifically the bony and cartilaginous components of the limb, while cells from the myotome eventually form the muscular components. The craniofacial cartilages arise from the ectoderm in response to cells migrating from the neural crest.
Advances in understanding vertebrate nephrogenesis
Published in Tissue Barriers, 2020
Joseph M. Chambers, Rebecca A. Wingert
Vertebrate development entails the formation of three germ layers, the ectoderm, mesoderm, and endoderm, which provide cellular blueprints for embryonic organogenesis. Ectoderm gives rise to the central nervous system and skin cells, and endoderm derivatives encompass cells that line the respiratory and digestive tracts. The mesoderm, or middle layer, produces cells that are most abundant in the human body constituting skeletal muscle, cartilage, heart, gonads, and blood, among other tissue types.1 This review will focus on a member of the mesoderm lineage: the kidney. Much of our understanding about kidney development stems from rodent models, but also has benefited from studies in other vertebrates such as fish, frogs, and birds.2The inception of mesoderm development begins with the differentiation of pluripotent epiblast cells into a transient ‘primitive streak’ zone.1Position along the anterior-posterior embryonic axis and other instructive signals regulate the regionalization of paraxial, intermediate, and lateral plate mesoderm.3
Dental stem cells in tooth regeneration and repair in the future
Published in Expert Opinion on Biological Therapy, 2018
Christian Morsczeck, Torsten E. Reichert
DPSCs are multipotent and trans-differentiate into non-dental tissue cells as well [22,31–33]. Among other tissues, they are strongly considered for the regeneration of degenerated neural tissues, because the dental mesoderm originates from neural crest cells and not as skeletal MSCs from the paraxial mesoderm or the lateral plate mesoderm [34]. Therefore, dental mesodermal cells are related to cells of the peripheral nervous system, and a close relation between DPSCs and neural tissue cells has recently been shown [6,35,36]. Arthur et al. have shown that DPSCs can differentiate into functionally active neurons under in vitro conditions and transplanted DPSCs facilitate endogenous axon guidance under in vivo conditions, making these cells attractive for the regeneration of disconnected nerve fibers [31,37]. DPSCs are also considered for the repair of the retina and the central nervous system. While the mode of action remains elusive, paracrine-mediated processes with a wide array of secreted trophic factors are highly considered for neural tissue regeneration [38,39]. In addition to neuronal tissue generation, DPSCs have also been used successfully for the regeneration of a number of other degenerated tissues, for example, for the regeneration of liver fibrosis and acute liver failure in murine animal models [40,41]. However, again we do not know much about molecular mechanisms, although paracrine-mediated processes are highly probable. Here, it is important to mention that DPSCs are highly influenced by the surrounding niche/scaffold [42] and seem to be better suited for use in dental regeneration [43].
Long non-coding RNA FENDRR reduces prostate cancer malignancy by competitively binding miR-18a-5p with RUNX1
Published in Biomarkers, 2018
Guanying Zhang, Guangye Han, Xinjun Zhang, Quanfeng Yu, Zeyu Li, Zhenhui Li, Jianchang Li
Using human transcriptome analysis, researchers have revealed that only a small part of genes are protein-coding and most of the transcribed RNAs are not translated (Kapranov et al.2007). The non-coding transcripts generally include ribosomal RNA (rRNA), transfer RNA (tRNA) and micro-RNAs (miRNA). Although these non-coding transcripts were once considered to be transcriptional “noise”, more and more evidence has shown they play important roles in various physiological and pathophysiological processes. Long non-coding RNAs (lncRNAs) with transcripts containing more than 200 nucleotides represents a less investigated class of non-coding RNAs (Chen et al.2013). The number of lncRNAs ranges from 10,000 to 20,0008 and only a small part of them has been identified. Emerging studies have shown that lncRNAs play crucial roles in the regulation of cell differentiation, proliferation and apoptosis (McHugh et al.2015). It should be highlighted that most identified lncRNAs are dysregulated in different types of cancer, playing an oncogenic or tumor suppressive role (Gibb et al.2011). Notably, lncRNAs are characterized by their tissue-specificity, which increase the possibility to use them as novel biomarkers and therapeutic targets (Crea et al.2014). It has been reported that lncRNAs have been implicated in PCa development and progression (Prensner et al.2011). FENDRR is an lncRNA with its gene 3099nts in length which located at chr3q13.31 and consists of four exons (Xu et al.2014). FENDRR is found to be specifically expressed in nascent lateral plate mesoderm and be essential for proper heart and body wall development in mouse (Grote et al.2013, Grote and Herrmann 2013). Through binding with both polycomb repressive complexe 2 (PRC2) and Trithorax group/MLL protein complexes (TrxG/MLL), FENDRR plays important roles in controlling chromatin structure and gene activity (Schuettengruber et al.2007, Khalil et al.2009). It is found that decreased expression of FENDRR is associated with poor prognosis in gastric cancer and FENDRR regulates gastric cancer cell metastasis by affecting fibronectin1 expression (Xu et al.2014). However, the biological role of FENDRR and its mechanism in PCa is not known.