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Embryology of the Spinal Cord, Peripheral Nerves, and Vertebrae
Published in Bernard J. Dalens, Jean-Pierre Monnet, Yves Harmand, Pediatric Regional Anesthesia, 2019
Bernard J. Dalens, Jean-Pierre Monnet, Yves Harmand
In stage 6 (two weeks of gestation), the germ-disc is didermic and consists of two layers of cells, the entoderm (ventrally) and the ectoderm (dorsally) which together constitute the embryonic disc (Figure 1.1). The first rudiments of the axial skeleton are mesodermal cells, which can be recognized in stage 7 (0.5- to 1-mm embryos, 16 to 17 d). These cells appear dorsally and differentiate as the prechordal plate (Figure 1.2). In stage 8 (1- to 1.5-mm embryos, 17 to 19 d), the notochord and dorsal ectodermal structures differentiate. As they develop, they set up the neural plate rostral to both the primitive streak and Hensen’s node (Figure 1.3).9
Mitochondrial Dysfunction and Hearing Loss
Published in Shamim I. Ahmad, Handbook of Mitochondrial Dysfunction, 2019
The ear starts its developmental during the 3 weeks after the fertilization; then during the 23 days period the otic placode is evident. As in any organ, the development of the ear has specific temporal and spatial changes, with many genes involved. At this time, there is a trilaminar embryo (ectoderm, mesoderm and endoderm). In the median ectoderm, the subjacent cells constitute the prechordal plate and notochordal plate. In the prechordal plate, the stomodeum forms. The mesoderm located lateral to the midline (paraxial mesoderm) is segmented in somitomeres. There are seven somitomeres from prosencephalon to the level of the otic placode. When the anterior neural tube closes, the otic placode and neural epithelium are separated for thin ectodermic, then the placode epithelium thickens.6 It is important to point out, that all the skeleton and connective tissue of the face are from neural crest origin.7
Prenatal Development of the Facial Skeleton
Published in D. Dixon Andrew, A.N. Hoyte David, Ronning Olli, Fundamentals of Craniofacial Growth, 2017
To complete this general picture of the cephalic end of the early embryo, the most anterior part of the embryonic disc that lies immediately in front of the prochordal plate becomes the cardiogenic area, in which mesenchymal cells give rise to right and left primitive endothelial heart tubes that fuse with developing blood vessels elsewhere in the embryo. Circulation within the cardiovascular system is established by the latter part of the 3rd week after gestation and is the first organ system to achieve a recognizable functional state (Moore, 1993).
Morphine ameliorates pentylenetetrazole-induced locomotor pattern in zebrafish embryos; mechanism involving regulation of opioid receptors, suppression of oxidative stress, and inflammation in epileptogenesis
Published in Toxicology Mechanisms and Methods, 2023
Fümet Duygu Üstündağ, İsmail Ünal, Ünsal Veli Üstündağ, Derya Cansız, Merih Beler, A. Ata Alturfan, Pınar Mega Tiber, Ebru Emekli-Alturfan
Oprd1 is homologous to human OPRD1 (opioid receptor delta 1). It has enkephalin and morphine receptor activity. It's a part of the opioid receptor signaling pathway. It is found in the central nervous system, notochord, prechordal plate, swim bladder bud, and trunk, among other places (Arévalo et al. 2018). Nielsen et al. (2017) reported that genetic polymorphisms in the Comt and Oprm1 genes, regardless of gender, as well as Oprd1 in males, may impact morphine analgesia variability in experimental pain models. oprm1 is a mu-opioid receptor-homologous gene in the zebrafish (Barrallo et al. 2000) has comparable pharmacological features to mu opioid receptor in mammals (de Velasco et al. 2009). The distribution of the oprm1 gene and protein has been shown in larval zebrafish (Bretaud et al. 2007; Sanchez-Simon and Rodriguez 2008). Morphine binds to mu opioid receptor, the delta, and the kappa opioid receptors. On the other hand, it binds to MOR, to exhibit its analgesic pharmacological effects (Pathan and Williams 2012). Sivalingam et al. (2020) investigated the effect of acute morphine exposure on the expressions of oprm1, cfos, and npas4a in brain by in situ hybridization and real-time PCR and reported increased oprm1 and npas4a mRNA levels in dorsal and ventral telencephalon, preoptic area, and in the hypothalamus but decreased signals in dorsal habenula.
Anatomic variations of the human falx cerebelli and its association with occipital venous sinuses
Published in British Journal of Neurosurgery, 2021
Safiye Çavdar, Bilgehan Solmaz, Özgül Taniş, Orhan Ulas Guler, Hakkı Dalçık, Evren Aydoğmuş, Leyla Altunkaya, Erdoğan Kara, Hızır Aslıyüksek
The cranial meninges including the falx cerebelli are derived from cells of the prechordal plate, unsegmented paraxial (parachordal) mesoderm, and mesectoderm (neural crest) in day 30 of human development.4 The development of the leptomeninges starts first followed by the dura mater. It has been shown that dura mater regulates events overlying skull by the release of growth factors. Morphogenesis of the cranial bones and sutures is dependent on tissue interactions with the dura mater, which control the size and shape of the overlying bones.5,6 As the formation of the intradural venous sinuses is concurrent with development of the dural folds, any alteration in the morphology of the dural folds may potentially be associated with variations of the venous sinuses. Thus, any variation of the falx cerebelli can involve the occipital sinus.