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Fibroblast-Pneumonocyte Factor
Published in Jason Kelley, Cytokines of the Lung, 2022
Many organs are composed of two different tissues, epithelium and mesenchyme. Mutual interactions of these two tissues have been demonstrated to be essential for the sequential events of organogenesis—determination, growth, morphogenesis, and cytodifferentiation (Bissell et al., 1982; Grobstein, 1967; Karkinen-Jaakelainen et al., 1977; Lash and Whittaker, 1974; Lash and Burger, 1977; Poste and Nicolson, 1977; Saxen, 1977; Wessels, 1977). The concept that these associated cell components act on each other to generate new and diverse cell types during organogenesis was initially termed embryonic induction (Grobstem, 1967), but it is now referred to as tissue interaction. In 1911, Peebles had already suggested that tissue interaction might play a very important role in organogenesis. Since Grobstein first demonstrated in 1953 the necessity of epithelial-mesenchymal interactions in the morphogenesis of various organs, many examples of such interactions have been described. Mesenchyme seems to play a predominant role in directing differentiation. These mesenchymal inductions have been classified into two types, inductive and permissive direction (Saxen, 1977), and the respective cellular responses are termed commitment and progression.
General Biological Aspects of Oncogenesis
Published in Pimentel Enrique, Oncogenes, 2020
In cultured neoplastic cells apparently spontaneous reversions with maturation and differentiation are occasionally observed.287-290 The cellular mechanisms associated with reversion phenomena are not understood but mutational events are apparently not responsible for these reversions because different types of mutagenic agents, including an alkylating agent, a frame-shift mutagen, and a treatment known to induce both chromosomal and point mutations, are unable to increase the frequency of revertants of hepatoma cultured cells.291 In contrast, the same cells can be heritably induced to differentiate following a short interval of culture in the form of aggregates, which suggests that increased cell contacts may elicit differentiation in vitro through mechanisms evoking those operating in embryonic induction phenomena in vivo.292 Obviously, such mechanisms would not be associated with mutations but would involve particular types of regulatory changes, most probably occurring at the genome level.
Mouth and throat, face, and the five senses
Published in Frank J. Dye, Human Life Before Birth, 2019
Embryonic induction: An important phenomenon in development is that of cascades of embryonic inductions. This is beautifully exemplified by the development of the eye. The retinas of the eyes are originally parts of the wall of the brain early in development. They eventually become pairs of outgrowths (evaginations) of the brain, which become, by ingrowths (invaginations), double-walled structures; that is, the retinas. These developing retinas induce the formations of lenses from the surface ectoderm of the head of the embryo. The paired lenses, in turn, induce the formations of the corneas of the eyes
Clinical Presentations and Diagnostic Imaging of VACTERL Association
Published in Fetal and Pediatric Pathology, 2023
Gabriele Tonni, Çağla Koçak, Gianpaolo Grisolia, Giuseppe Rizzo, Edward Araujo Júnior, Heron Werner, Rodrigo Ruano, Waldo Sepulveda, Maria Paola Bonasoni, Mario Lituania
The word “association”, by definition, is different from “syndrome”. A set of related symptoms characterizes syndromes, whereas associations are nonrandom interactions. Associations represent the idiopathic occurrence of multiple congenital anomalies during blastogenesis. The key concept is the implication that different causal factors, acting at certain stages in development, cause similar patterns of defects [17]. Developmental defects occurring during blastogenesis are polytopic and originate in two or more progenitor fields, for instance, anorectal anomalies. Monotopic defects arise during organogenesis, which involves one genetic field. Polydactyly, one of the many clinical symptoms of VACTERL association, is caused by a monotopic defect during organogenesis. “Clinical heterogeneity” depends on when the different factors (genetic and/or environmental) act, therefore resulting in either an isolated developmental field defect (DFD) or a DFD associated with other patterns of malformations. The development field is a region or part of the embryo which responds as a coordinated unit to embryonic induction and results in complex or multiple anatomic structures [18]. Etiological heterogeneity is one of the known characteristics of the DFD.
Exosomes as secondary inductive signals involved in kidney organogenesis
Published in Journal of Extracellular Vesicles, 2018
Mirja Krause, Aleksandra Rak-Raszewska, Florence Naillat, Ulla Saarela, Christina Schmidt, Veli-Pekka Ronkainen, Geneviève Bart, Seppo Ylä-Herttuala, Seppo J. Vainio
The embryonic kidney represents a classic model system that has been used to study the cellular and molecular mechanisms of cell and tissue interactions collectively named as a process of embryonic induction. Inductive interactions occur also later during organogenesis, and in the kidney, for example, these occur between epithelial and mesenchymal tissues [48]. Such molecules that mediate the embryonic inductive interactions and are involved in the associated pattern formation are called the morphogens [48,49]. A wealth of data have been generated that indicate a role for several growth factors in the inductive cell and tissue interactions such as the FGFs, TGF beta/BMP, Hedgehog and Wnt signals [50,51] but whether these serve as morphogens is still debatable. The identification of the exosomes and the data presented herein raise the possibility that the exosomes serve as a novel but apparently evolutionary ancient embryonic signalling system. The embryonic kidney model system derived data presented here confirm that indeed RNA species are transferred in association with the process of embryonic induction, being a universal mechanism in the coordination of morphogenesis. Thus, we can conclude that the exosomes provide a newly identified source of signalling with putative relevance to organogenesis. However, the mechanisms by which exosomes act in nephrogenesis remain to be investigated.