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Molecular interaction of developing axons with the surface ectoderm
Matějček, Miroslav ; Machoň, Ondřej (advisor) ; Rozbeský, Daniel (referee)
The complex of cranial nerves consists of twelve pairs of nerves, which connect organs of the head with the central nervous system. One of the organs, which are innervated by cranial nerves are whiskers (also known as vibrissae). Whiskers are special type of mammalian hairs, which are innervated by the infraorbital branch of trigeminal nerve. These hairs provide information necessary for orientation in terrain, localisation of prey and locomotion. The potential role of axons in whiskers development has been discussed for many years. However, this hypothesis has not yet been confirmed. In this research we have used murine strains Neurog1 KO and Meis2 cKO with either abnormal or completely missing trigeminal nerve. Thanks to the analysis of embryonic development in these strains we have denied our hypothesis, that axons of trigeminal nerve serve a role in initiation of whisker follicles. In Meis2 cKO embryos we observed malfunction in formation of whisker follicles. The expression of Meis2 during the development of whiskers has an influence on various signalling cascades including Fgf, Shh and Bmp. In regards to changes in mentioned signalling cascades we suggest that the whisker follicle development is altered between the first dermal and first epidermal signal.
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Heart Rate Response in Newborns to Relatively Strong and Mild Trigeminal Odorants
Boušová, Jiřina ; Martinec Nováková, Lenka (advisor) ; Brothánková, Pavlína (referee)
The widely accepted view nowadays is that experiencing odours as rather pleasant or unpleasant is, to a certain degree, shaped on a daily basis through individual experience within one's culture via evaluative conditioning or, rather marginally so, via mere exposure to that certain odour. In other words, humans are not born with any fixed set of olfactory likes or dislikes but rather, they acquire them throughout their lifetime. However, olfactory sensation is not a "pure" percept, as odorant stimuli generally elicit a qualitative percept of an odorant - generated mainly by the olfactory nerve - as well as some degree of chemesthesis - a tactile confound of the odour generated mainly by the trigeminal nerve. The olfactory and trigeminal system exhibit complex interactions at both the peripheral and central level of chemosensory processing, which is also reflected in perceptual characteristics of the final percept, including perceived pleasantness (hedonics). If the olfactory contribution alone does not easily predict neonatal odour hedonics, due to newborns' limited previous exposure to chemosensory inputs, one may hypothesize that together with the strength of the trigeminal contribution they may form a significant factor affecting neonatal appetitive/aversive responses to odours. In the present...
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