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Role of transcription factors MEIS in the origin and development of the neural crest
Fábik, Jaroslav
Unique to the vertebrate embryo, neural crest cells represent a multipotent cell population that migrates throughout the body and gives rise to a multitude of different types of cells and tissues. Cranial neural crest cells populate the developing pharyngeal arches and establish skeletogenic condensations that generate the future bones and cartilages of the face and neck. Moreover, these cells send out and receive signals from adjacent tissues of non-neural crest origin, such as the mandibular epithelium and muscle precursor cells. Such reciprocal interactions give rise to organs and structures, for instance, to the tongue. The aim of this work was to elucidate the roles of homeodomain-containing MEIS transcription factors in neural crest cells and in craniofacial development, by using a mouse model with conditional inactivation of Meis2 gene in neural crest cells. We show that transcription factor MEIS2 is expressed in the medial region of the developing mandible and in the developing tongue. Conditional Meis2 inactivation using the Wnt1-Cre2 mouse strain caused mandible and tongue hypoplasia, and ectopic bone formation at the expense of tongue development. These mandibular arch anomalies were accompanied by the loss of Hedgehog signaling in the mandibular epithelium, expanded RUNX2 expression in...
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Role of transcription factors MEIS in the origin and development of the neural crest
Fábik, Jaroslav ; Machoň, Ondřej (advisor) ; Buchtová, Marcela (referee) ; Procházka, Jan (referee)
Unique to the vertebrate embryo, neural crest cells represent a multipotent cell population that migrates throughout the body and gives rise to a multitude of different types of cells and tissues. Cranial neural crest cells populate the developing pharyngeal arches and establish skeletogenic condensations that generate the future bones and cartilages of the face and neck. Moreover, these cells send out and receive signals from adjacent tissues of non-neural crest origin, such as the mandibular epithelium and muscle precursor cells. Such reciprocal interactions give rise to organs and structures, for instance, to the tongue. The aim of this work was to elucidate the roles of homeodomain-containing MEIS transcription factors in neural crest cells and in craniofacial development, by using a mouse model with conditional inactivation of Meis2 gene in neural crest cells. We show that transcription factor MEIS2 is expressed in the medial region of the developing mandible and in the developing tongue. Conditional Meis2 inactivation using the Wnt1-Cre2 mouse strain caused mandible and tongue hypoplasia, and ectopic bone formation at the expense of tongue development. These mandibular arch anomalies were accompanied by the loss of Hedgehog signaling in the mandibular epithelium, expanded RUNX2 expression in...
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Comparative development & evolution of adenohypophysis in basal fishes
Brezarová, Dominika ; Černý, Robert (advisor) ; Buchtová, Marcela (referee)
The pituitary is a master endocrine gland in the vertebrate head with many crucial roles in producing hormones and controlling secretion of other glands, and with long-standing controversies on its evolution and embryonic origin. Adenohypophysis (ADH), the front lobe of the pituitary, develops from the rostral placode that extensively migrates under the brain to connect the neurohypophysis, evagination of the ventral hypothalamus. Owing to its ectodermal placodal origin, ADH is commonly understood as a part of the vertebrate specific acquisition of our new head. Recently, however, an endodermal contribution to ADH was revealed in the teleost fish, supporting classic claims of a pre-vertebrate origin of this organ from an ancient chordate pharyngeal structure. In this work, early development of ADH was characterized in three species of basal fishes, bichirs, sturgeons, and gars, representing a possible stem-like pattern of early vertebrate craniogenesis. Interestingly, in all three species, both the early development and later migration of ADH is intimately linked with the pharyngeal domain in the rostral head. In sturgeon embryos, ADH migrates in between the brain and the pharyngeal domain, which further separates ADH from the forming mouth. In bichir embryos, ADH was additionally shown to get...
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Comparative development & evolution of adenohypophysis in vertebrates
Brezarová, Dominika ; Černý, Robert (advisor) ; Kozmikova, Iryna (referee)
Adenohypophysis is very important gland in vertebrate head. In general adenohypophysal development is described together with formation of the primary mouth. Adenohypophyseal placode migrates together with stomodeal placode in ventral direction. Stomodeal placode starts to invaginate and from oral ectoderm adenohyphyseal placode invaginates to form Rathke's pouch. Pouch is then separated from mouth and migrates towards the brain to make adult hypohyseal gland. Origin of adenohypophysis is therefore in oral ectoderm, but in some vertebrates species is this development little different and adenohypophysis can even be endodermal. In some vertebrate groups, like amphibians or fishes there's no sign of Rathke's pouch, thus early migrations of adenohypophyseal placode can be different. These differences are there maybe because these groups don't have shallow invagination of stomodeum like other vertebrates. There are some homological structures in other chordate groups, for example Hatshek's pit in amphioxus or neural gland in tunicates, these structures has, in contrast with vertebrates, endodermal origin. Key words: adenohypohysis, placodes, primary mouth, craniofacial development, Rathke's pouch, vertebrates
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