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Sonic hedgehog is one of three members of the Hedgehog family, whose signaling pathway plays a crucial role in controlling the development of vertebrates. Sonic hedgehog has an important role in organizing the developmental processes of majority of organ systems. Interestingly, its direct expression or a contribution of cell lineages expressing this signaling molecule in the myocardium has never been described. The aim of this work was to try to detect the cells that expressed Sonic hedgehog directly in the heart tissue with a focus on the myocardium. We monitored these cells from embryonic day 10.5 to 16.5 and then postnatally. We also evaluated current Sonic hedgehog expression in cardiac tissue from embryonic day 12.5 to embryonic day 15.5. We used the CreLoxP system, X-gal staining, fluorescence and confocal microscopy to detect cell lines expressing Sonic hedgehog. We also assessed the presence of cells that expressed Sonic hedgehog in the developping heart in the past using immunohistochemistry. According to our results, the presence of a descendant cell lineage expressing Sonic hedgehog in the past was demonstrated prenatally and postnatally in the mouse myocardium. The performed analysis shows that these cells can be detected in cardiac tissue from embryonic day 10.5 till the postnatal...

Body appendages of vertebrates are structures developing during embryonal stages through lateral outgrowth from main body axis. Despite their different composition and high diversity, all these structures are organised along three main axes. Antero-posterior polarization is the most significant in body appendage differentiation. These polarized differentiation changes are best understood in the limbs, where they are controlled by the organizing centre named zone of polarizing activity (ZPA). This centre interacts with another centre named apical ectodermal ridge (AER), which mainly governs limb outgrowth laterally from the body axis. ZPA produces Sonic hedgehog (Shh), along with other signalling molecules participating in the polarization. Shh is a key part of highly conserved signalling pathway common to polarized structures and is influenced by retinoic acid (RA), which plays role in the ZPA creation. ZPA activity stimulates secretion of fibroblast growth factors (Fgf) and bone morphogenic proteins (Bmp). All these signalling pathways ensure correct differentiation of appendages through interaction and concentration-dependent mechanisms. The goal of this thesis is to introduce the mechanisms of polarization in other appendages, such as external genitalia and branchial arch derivates to the reader,...

Stem cells are non-differentiated self-renewing cell population that can derive different kinds of cell types according to their differential potential. Neurogenic differentiation is the process of generating of all three types of nervous systems from the neural stem cells. This process is common for embryonic development, however neurogenesis appears to be present also in adult mammalian brain. It continues to generate new neurons within its microenvironments called niches and we can find two major areas of neurogenesis. One is the subventricular zone of the forebrain, the other is the subgranular zone within the hippocampal dental gyrus. In these niches we can find specific signaling molecules called morphogens. Morphogens function in regulating neural stem cell activity. They play a part in proliferation, differentiation and cell migration, thus determining the fate of neural cells. In addition, morphogens play an important role in many diseases and cancers.

In vivo organogenesis is based on the temporal-spatial developmental processes that depend on cell behaviour, for example on their growth, migration, differentiation and intercellular interactions. Such behaviour is regulated by appropriate transient expression of various signalling molecules. Despite the significant advances in therapeutic strategies, the secret of the development of the biological replacement of a damaged or missing tooth has not yet been revealed. In this context, animal models provide a powerful tool for studying tooth normogenesis and pathogenesis in both basic and applied research. Early development of the tooth shares similar morphological and molecular features with other ectodermal organs. At the same time, these features are largely preserved also between species, which is advantageous for the use of model organisms. The dental formula of both: the human and the mouse are reduced against a common ancestor, but both groups of organisms evince simple as well as multicusped teeth. In both, structures called rudimentary were found. These structures are suppressed during ontogenetic development and generally they are not attributed to essential functions. That is why we aimed to study dental rudiments in detail and reveal their function in odontogenesis. This work presents new...