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Gonadal development during the lifetime of the fastest maturing model vertebrate- turquoise killifish (Nothobrachius furzerí)
LANDOVÁ, Magdaléna
Turquoise killifish had to adapt to the inhospitable conditions in which they live, especially drying temporal water bodies, which means certain death. The life sprint of the representatives of this genus is at its peak within one-month post-hatching, when both sexes have fully developed gonads and can reproduce. This rate comes with a high cost, as the killifish gonads begin to show signs of tissue degradation and germ cell apoptosis as early as three months post-hatching. Germ cell loss increases with age. A description of the development and degradation of the gonads in males and their breeding was elaborated. For the evaluation of aging-specific changes, immunochemical methods were used, focusing on the binding of specific antibodies against target epitopes and their visualization using fluorescence microscopy. Procedures for histological specimens have also been described, both for classical light and fluorescence microscopy.
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Gametogenesis and Fertilization in Humans
Crhová, Michaela ; Pavlasová, Lenka (advisor) ; Ehler, Edvard (referee)
This bachelor thesis summarises the topic of gametogenesis and fertilization in humans. A search in available literature was performed. The thesis concisely describes the cell cycle and cell division. The main focus is on meiosis, a reductional division that takes the lead part in sexual reproduction. The process of this division is described in detail, and also the mechanism that creates variability of protected cells is described. The product of meiosis is gametes, also known as germ cells. Production of these cells is a key moment in sexual reproduction. This thesis approaches this topic in the context of evolutionary biology and explains its importance in the survival of species on Earth. The main topic of the thesis is the production and maturing of human germ cells. This process is called gametogenesis. This thesis provides a cohesive description of the reproduction system of both sexes and describes the gradual maturing of the germ cells in gonads. The structure of both gametes, egg, and sperm is described with emphasis on the parts of these cells that take part in the process of fertilization. Female reproductive cycles are depicted, and their connection is explained. In contrast to this periodicity, the male continual maturing is also explained. This thesis compares the main differences in...
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Expression of Heme oxygenase Isoforms during aging of porcine oocytes.
Poupalová, Michaela ; Sedmíková, Markéta (advisor) ; Lenka, Lenka (referee)
Quality and fertilization rate of oocytes matured in vitro conditions is essential for their use in biotechnology. Many morphological and functional changes occurs in oocytes during prolonged cultivation, which result in decreased fertilization rates and higher levels of apoptosis, polyspermy, parthenogenesis and chromosomal anomalies. These changes also have a negative effect on subsequent embryonic development. Understanding the mechanisms of oocyte aging could thus make a major contribution to the development of reproductive biotechnologies in livestock and human assisted reproduction.
The enzyme heme oxygenase (HO) catalyzes the oxidative cleavage of heme to biliverdin, carbon monoxide (CO) and ferrous ions. There are two isoforms of heme oxygenase, i.e. HO 1 and HO 2. HO 1 has cytoprotective properties and in the cells is expressed especially in response to stress factors. HO 2 is responsible for basal production of CO. CO belongs to gasotransmitters, which are endogenously produced signaling gaseous molecules. Meaning of HO/CO system was proven in reproductive system of both males and females. Its importance in oocytes is not known.
The aim of this thesis was to verify the hypothesis that the HO is expressed in porcine oocytes during their prolonged cultivation in vitro conditions and that the expression of both isoforms changes during aging. Oocytes were evaluated at the metaphase stage of the second meiotic division (MII) and three stages of aging according to the length of prolonged cultivation, i.e. 24, 48 and 72 hours. HO 1 and HO 2 were localized by immunocytochemistry method.
By evaluating the experiments it was confirmed that both HO isoforms are expressed during aging in all evaluated areas, i.e. in the perichromosomal area, cortical area and cytoplasm. HO 1 is located mainly in the perichromosomal area and during aging occurs statistically significant increase in signal intensity. In the cortical area and the cytoplasm was detected statistically significant difference only in oocytes aging 72 hours and the signal intensity is weaker in these areas.
In the case of HO 2 signal is evenly distributed throughout the oocyte and compared with the HO 1 the signal is significantly stronger. A statistically significant increase in signal intensity occurred between oocytes at the MII stage and the group of oocytes aging 24 hours. An expression of HO 2 compared with matured oocytes significantly increases during prolonged cultivation.
A scientific hypothesis was confirmed in the case of both HO isoforms, i.e. HO 1 and HO 2 were localized in aging porcine oocytes and at the same time there is a change in expression during prolonged cultivation. From the results of experiments it can be assumed that products of enzymatic activity of HO-1 and HO-2, including CO are also present in oocytes, and therefore HO/CO system is probably related to the oocyte aging. The assumption is that HO 1 acts as a cytoprotective factor, which could have a possitive effect on oocyte quality. HO 2 is responsible for basal production of CO, but it may also play a role in the regulation of oxidative stress in oocytes.
The data obtained should be investigated further with more experiments focused on localization and redistribution of both isoforms during oocyte aging. The subject of further research should also be a mechanism of action and specific function of HO 1 and HO 2 in oocytes.
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Oogenesis in long-lived water bug Velia caprai (Heteroptera: Gerromorpha: Veliidae)
MÁLKOVÁ, Karolína
This thesis presents results of the histological study of oogenesis in the nymphs of 5th instar, variously aged adult females of known age and adult females of Velia caprai ((Heteroptera: Gerromorpha: Veliidae) of unknown age that were collected in the field. Oogonia in the germarium and the first oocytes that are forming in previtellarium were observed in the nymphs of the 5th instar. Their vitellarium is empty. The first vitellogenetic oocytes appear in vitellarium of ovarioles at 7 days old adult females. Oocytes in advanced stage of vitellogenesis were observed at 25 days old adult females. The secretion of chorion starts at 42 days old adult females. Advanced stage of oogenesis (fully chorionated eggs) was found at 60 days old adult females, at adult females collected in the field, during the period September ? November (2009), and at adult females after overwintering. Females of Velia caprai reach sexual maturity before overwintering, their eggs can be fertilized by spermatozoa from own spermatheca. These females can lay eggs from autumn to the spring. After reaching sexual maturity of adult females, oogenesis of this species seems to be continual.
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