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Rhythmic non-light maternal signals, such as various behavioral, neurohumoral or metabolic factors, may play a key role in synchronization of the fetal circadian clock. This diploma thesis focuses more closely on the possible role of leptin and dopamine in the hormonal synchronization of the fetal central clock resides in the suprachiasmatic nuclei of the hypothalamus. A transgenic mouse fetus, which has luciferase fused to the clock gene Period 2, was used as an experimental model. This allowed us to monitor the operation of the fetal central clock in real time by recording the bioluminescence of tissue explants. Exogenous administration of dopamine during the decline in bioluminescence at normalized circadian time 15 induces larger phase delays compared to vehicle. Leptin, on the other hand, can participate in the development of spontaneous rhythms by stabilizing the integrity of the circadian rhythm, manifested by slowing down the rhythm dampening. At the level of individual cellular oscillators, significant regional differences in amplitude and period were not observed using bioluminescence microscopy. However, a slight dispersion of cell phases was observed after administration of dopamine during decreasing bioluminescence. In the case of leptin, there was a prolongation of period of the cell...

One of the factors influencing the successful outcome of assisted reproduction could be the oxidative stress (OS), which is characterized by a disequilibrium between prooxidants and antioxidants in favour of prooxidants. Important prooxidants are both radical and non-radical reactive oxygen species (ROS) with a high reactivity and strong oxidizing effects on biological substrates. The origins of ROS and OS are assisted reproductive technologies (ART) and several exogenous sources to which gametes and early embryos are exposed during in vitro manipulation. The overproduction of ROS is associated with several negative effects on the cellular and molecular level. However, ROS are a common part of the cellular metabolism and important signaling molecules participating in processes necessary for the physiological development of gametes and early embryos. Hence, strategies to reduce OS may lead to improved results in assisted reproduction. The purpose of this bachelor's thesis is to provide a comprehensive review of literature focused on the identification of sources of ROS and OS, their effect on gametes and early embryos, as well as the possibilities for OS reduction and improvement of cultivation conditions in ART in human. Key words: oxidative stress, reactive oxygen species, gametes, early embryo,...