Time-Lapse Analysis of Living Mouse Germ Cell Migration

Abstract

In mouse embryos, the primordial germ cells arise during gastrulation prior to, and distant from, the prospective gonads. Observations of PGCs in culture, and in fixed sections, have suggested, but not proved, that they migrate to the gonad by a process of active migration. The opaque nature of the early mouse embryo has precluded direct observation. Using confocal microscopy, we have filmed living PGCs expressing eGFP in tissue slices from mouse embryos at different stages of development. We find four clearly distinct phases of PGC migration. First, until E9.0-E9.5, PGCs are already highly motile, but do not leave the gut. Second, in the E9.0-E9.5 period, before the mesentery forms, PGCs very rapidly exit the gut, but do not migrate towards the genital ridges. Third, during the E10.0-E10.5 period, PGCs migrate directionally from the dorsal body wall into the genital ridges. In contrast to the prevailing model of germ cell migration, very few, if any, PGCs found in the gut mesentery at E10.5 migrate into the genital ridges. Finally, at E11.5, PGCs are slowing and the direction of movement is dependent on the sex of the embryo. This allows, for the first time, a formal description of the events of PGC migration in the mouse.

Deleted in Azoospermia-Like Enhances In Vitro Derived Porcine Germ Cell Formation and Meiosis

“…Indeed, Dazl is required for gametogenesis, as its knockout results in the complete lack of a PGC population [8,18]. In addition, the expression of DAZL in 12.5-dpc PGCs (a time point that coincides with the mitotic to meiotic transition) is 28-fold higher than in 10.5-dpc (mitotic) PGCs in mice [19], suggesting that it may also play a role during meiosis. It has been reported that DAZL is necessary for the expression of Stra8 and meiotic initiation in embryonic ovaries, indicating that it is an intrinsic meiotic competence factor having an obligatory function upstream of meiotic initiation [20].…”

Cell biology of embryonic migration

“…This migration takes place over a considerable period of time (5 embryonic days for a mouse embryo, which constitutes approximately ¼ of the entire development), and is believed to occur in stages of rapid migration followed by relatively stationary periods (Molyneaux and Wylie, 2004;Molyneaux et al, 2001). The actual speed of this migration is difficult to estimate, because as the cells migrate, the embryo itself continues to grow and increases several times in size during the migration process (Fig.…”

Derivation of Human Embryonic Germ Cells: An Alternative Source of Pluripotent Stem Cells

“…These 'precursor' cells normally progress in vivo to form the complete embryo, including the diploid primordial germ cells (PGCs). During development, PGCs migrate from the posterior endoderm of the yolk sac via the gut mesentery to populate the developing gonads, where they proliferate and, ultimately, undergo meiosis to yield spermatozoa or ova [10]. When postimplantation fetuses are obtained following first trimester termination of pregnancy, PGCs can be isolated from dissected premeiotic fetal gonads for the derivation of diploid hEG cells [8].…”