National Repository of Grey Literature 60 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Migration and morphogenesis of neural crest cells in the context of craniofacial development of selected ray-finned fishes
Štundl, Jan ; Černý, Robert (advisor) ; Buchtová, Marcela (referee) ; Machoň, Ondřej (referee)
Neural crest (NC) cells play a crucial role in vertebrate development and evolution. This cell population contributes to many new cell types such as chondrocytes and osteocytes of the head skeleton, neurons, pigment cells, cardiomyocytes, and many others. As such the neural crest is often considered as the fourth germ layer. This vertebrate-specific cell population emerges during formation of the neural tube. Whereas in the trunk region NC cells migrate as separate cells, cranial neural crest (CNC) cells extensively migrate in three discrete streams forming most of the head mesenchyme. In all vertebrates, CNC stereotypically follows the tripartite pattern of migration along the anteroposterior axis so that the most anterior (trigeminal) stream emerges first, followed by the hyoid and branchial CNC streams. In this work, I have studied representatives of all three lineages of non-teleost fishes (bichir, sturgeon, and gar) and also one species from the crown group of ray-finned fishes, the pike. The main question I addressed in my project was whether the CNC cells stereotypically follow a tripartite pattern of migration along the anteroposterior axis as is seen throughout vertebrates. Surprisingly, I found several alterations in the emergence of CNC cells and their migratory pattern in the studied...
Primary mouth formation in basal fishes
Psutková, Viktorie ; Černý, Robert (advisor) ; Šindelka, Radek (referee)
The mouth is a crucial structure for every organism since it forms an important connection between internal and external environments. The primary mouth develops from the ectodermal-endodermal region at the anteriormost part of the forming head during early embryogenesis. In the majority of vertebrates the primary mouth develops through the stomodeal invagination, establishment of the oral membrane, and by its rupture the mouth gets opened. However, the mouth development significantly differs in several groups of vertebrates and the three main modes of the mouth development were recognized according to ectoderm-endoderm interactions. The most common is "stomodeal invagination", the "stomodeal collar" is in salamanders and lungfishes, and "stomodeal wedge" in teleosts. Here, I analyse the development of the oral region in embryos of basal actinopterygian fishes, bichir (Polypterus senegalus), sturgeon (Acipenser ruthenus) and gar (Atractosteus tropicus), which could give us better understanding of the evolution and morphogenesis of the primary mouth in vertebrates. In bichir embryos, the mouth development generally resembles development of the stomodeal wedge in teleost fishes, with some morphogenetic differences. In sturgeons, the mouth forms via modified stomodeal collar, whereas in gars the mouth...
Trabecula cranii: viscerocranial element of the new vertebrate head
Horáčková, Agáta ; Černý, Robert (advisor) ; Minařík, Martin (referee)
4 Abstract Trabeculae cranii comprise major paired elements that constitute cartilaginous basis of the rostral embryonic skull. Trabeculae were initially recognized as remnants of the pre-mandibular visceral arch. This assumption is originally based on the segmentation theory, that the vertebrate head is segmented in the same metameric pattern as the trunk. This theory is not considered valid anymore. Contemporary authors also reject the possibility, that the trabecula is a part of viscerocranium, even though it shares some developmental patterns with pharyngeal arch elements. The key character of a viscerocranial element should be it's developmental relationship with the endoderm. If the trabecula represents a pharyngeal cartilage, it will develop in a topographical relationship with the pre- oral gut endoderm. Basal actinopterygian fishes (African bichirs, European sturgeons, and Tropical gars) offer unique opportunity to examine this hypothesis because of recent description of the pharyngeal pouch-like component in the pre- mandibular head segment, which most likely represents an ancestral vertebrate character. In these fishes, the topographical relationship of trabeculae and endoderm was found using histological analyses, antibody stainings, and fate- mapping experiments. This work shows that trabeculae...
The embryonic development of the pharyngeal region in vertebrates
Píchová, Lenka ; Černý, Robert (advisor) ; Minařík, Martin (referee)
The fully-formed pharynx is for adult vertebrates indeed a vital structure. The pharynx provides two main functions - dealing with food and breathing. During embryonic development, pharynx is visible like a series of bulges on the lateral surface of the head. Embryonic development of the pharyngeal region starts with evagination of the endoderm to form the pouches, opposit to that the ectoderm invaginates to form the ectodermal clefts. Pharyngeal arches are formed after fusion of these epithelial layers, and pharynx is thus bordered by ectoderm from the inner, and endoderm from the outer side. Each pharyngeal arch consists of mesenchymal core of mesodermal and neural crest derived cells. All vertebrates develop through the so called phylotypic stage, being represented by the - pharyngula with the present pharyngeal arches. Accordingly, it was generally believed that development of the pharyngeal region is rather conservative in all vertebrates. My comparative analysis of pharyngeal development in different vertebrates species reveals that - only early embryonic formation of pharyngeal arches seems conserved, however, that later in development pharyngeal arches form various and diverse derivatives. Key words: Vertebrates, ectodermal fleft, endodermal pouch, pharyngeal arches, neural crest
Migration and skeletogenesis of trunk neural crest cells
Suchánek, Tomáš ; Černý, Robert (advisor) ; Mašek, Jan (referee)
The neural crest is specific cell population of vertebrates embryos. It emerges in dorsal part of the neural tube from which it separate as individual cells. After that, these cells migrate throughout the embryo to their final destination. There they are exposed to a molecular signals and then they differentiate into various types of derivatives. The neural crest is distinguished into two main parts - cranial and trunk. While the cranial neural crest has been in the forefront of interest due its skeletogenic potential and participation in formation of the "new head", the trunk neural crest had been neglected due its "less attractive " derivates. Hence this bachelor thesis is focused on trunk neural crest. Especially it highlights the migratory behavior of trunk neural crest cells and its skeletogenic potential which represents opportunity for prospective research about neural crest.
Method of Lagrange multipliers in Calculus of Variations
Borák, Vojtěch ; Černý, Robert (advisor) ; Hencl, Stanislav (referee)
Tato práce řeší několik základních příkladů z variačního počtu a demonstruje prospěšnost zamyšlení se a případné pozměnění úlohy bez snížení dimenze za přítomnosti vazeb. Všechny úlohy jsou řešeny metodou Lagrangeových multipli- kátorů. Především v konečné dimenzi demonstruje hypotézu autora ohledně ne- snižování dimenze problému klasifikace definitnosti diferenciální formy druhých derivací a ukazuje jednak příklad, ve kterém je autorův nápad prospěšný, i pří- klad, kde svádí na scestí. 1
Comparative and evolutionary analyses of neurulation in non-teleost fishes
Matějková, Tereza ; Černý, Robert (advisor) ; Pergner, Jiří (referee)
Neurulation, i. e. formation of a neural tube, is a crucial event in embryogenesis of each vertebrate. This developmental process is rather stereotypical, generally comprising a transformation of a neural plate into a neural tube. In the majority of vertebrate groups, neurulation classically occurs by a folding process of bending neural folds, whereas in bony fishes (Teleostei), representing a crown group of ray-finned fishes (Actinopterygii), the neurulation occurs rather differently by a solid neural keel. The three stem groups of ray- finned fishes - bichirs, sturgeons and gars - might thus serve as unique models for understanding of evolutionary changes in the pattern of vertebrate neurulation. For that reason, detailed developmental series of bichir (Polypterus senegalus), sturgeon (Acipenser ruthenus) and gar (Atractosteus tropicus) were used, and their morphogenetic processes of neurulation were compared. I present here description of the outer morphology, and analyses of tissue and cellular changes, with a focus on intrinsic forces within the neural plate like apical constriction and convergent extension, as well as on some extrinsic forces. I also try to discuss possible mechanisms of an evolutionary transition from the bending of the neural plate to the neurulation via the neural keel,...

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