Meiotic division of a female germ cell, an oocyte, is more prone to segregation errors and consequently to aneuploidies than meiosis of a sperm. Aneuploidies and chromosomal aberrations in oocytes increase with higher maternal age in humans and also in mice. Meiotic maturation onset is connected with activity of cyclin dependent kinase 1 (CDK1) that leads to dissociation of nuclear membrane. Moreover regulation of translation of key transcripts is necessary for proper meiotic progression. In thesis findings from four scientific publications are interpreted. We have analyzed the timing of nuclear envelope breakdown (NEBD) and polar body extrusion in mouse oocytes originating from two distinct female age groups: young (2 months old) and aged (12 months old). We found that meiotic maturation happens faster in aged females' oocytes due to early phosphorylation of Lamin A/C, a component of nuclear lamina, and rapid dissociation of nuclear membrane. Moreover aged females' oocytes presented unique characteristic invaginations of nuclear membrane and thus significantly increased circumference of the nuclear envelope compared to the oocytes from young females. These data combined with increased activity of CDK1 and Cyclin B, as well as increased translation of factors that regulate the translation itself,...

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