Gametes are cells that have the unique ability to give rise to new individuals as well as transmit (epi)genetic information across generations. Generation of functionally competent gametes, oocytes... Show moreGametes are cells that have the unique ability to give rise to new individuals as well as transmit (epi)genetic information across generations. Generation of functionally competent gametes, oocytes and sperm cells, depends to some extent on several fundamental processes that occur during fetal development. Direct studies on human fetal germ cells remain hindered by ethical considerations and inaccessibility to human fetal material. Therefore, the majority of our current knowledge of germ cell development still comes from an invaluable body of research performed using different mammalian species. During the last decade, our understanding of human fetal germ cells has increased due to the successful use of human pluripotent stem cells to model aspects of human early gametogenesis and advancements on single-cell omics. Together, this has contributed to determine the cell types and associated molecular signatures in the developing human gonads. In this review, we will put in perspective the knowledge obtained from several mammalian models (mouse, monkey, pig). Moreover, we will discuss the main events during human fetal (female) early gametogenesis and how the dysregulation of this highly complex and lengthy process can link to infertility later in life. Show less
In this thesis, Chapter 1 presents the state of the literature on early development in humans and mice. Chapter 2 describes the development of gonadal and extragonadal PGCs in humans. Chapter 3... Show moreIn this thesis, Chapter 1 presents the state of the literature on early development in humans and mice. Chapter 2 describes the development of gonadal and extragonadal PGCs in humans. Chapter 3 investigates the status of XCI in human pre-implantation embryos. One X chromosome is indicated to be inactive in E4-E6 cells and E7 trophectoderm cells, whereas it becomes reactivated in E7 epiblast and primitive endoderm cells. Chapter 4 describes the entering of EVTs in maternal circulation (via decidual veins and lymphatic vessels) starts since W5.5, much earlier than previously accepted W8 (via decidual spiral arteries). Chapter 5 studies the spatial imprinting pattern of IGF2/H19 in human first-trimester placental villi. A normal imprinting pattern of IGF2/H19 is revealed in multi-site villi collections as in the embryo. Chapter 6 explores different consequences of Turner syndrome in mouse placenta. The significantly larger area of glycogen cells in XpO placental outer zone and the significantly higher expression of Ldha in XpO labyrinth zone suggest a more severe placental phenotype in E18.5 XpO placentas than in XmO placentas. Finally, Chapter 7 provides general discussion about the findings and discusses the future perspectives on assisted reproduction and new treatment for infertility, pregnancy complications. Show less
Primordial germ cells (PGCs) are the progenitors of the gametes, responsible for transmitting genetic information from generation to generation. Although there is a long history of gamete biology... Show morePrimordial germ cells (PGCs) are the progenitors of the gametes, responsible for transmitting genetic information from generation to generation. Although there is a long history of gamete biology research, there is still a lot to be learned about many of the mechanisms underlying germ cell development. This dissertation describes and discusses the dynamics of PGCs in the chicken, with a focus on their migration to the gonads and meiosis that takes place when PGCs are already settled there. We also discussed the advantages of using the avian model in epithelial ovarian cancer research. Moreover, we revisited an often overlooked model for amniogenesis in which the proamnion plays a crucial role. Show less
Bialecka, M.; Young, T.; Lopes, S.C.D.; Berge, D. ten; Sanders, A.; Beck, F.; Deschamps, J. 2012
