During spermatogenesis, diploid stem cells differentiate, undergo meiosis, and transform into haploid spermatozoa. As this precisely timed series of events proceeds, chromosomal ploidy is reduced, and the nucleosomes of the chromatin are replaced by a transcriptionally quiescent protamine-containing
Mechanisms of germ-cell specification in mouse embryos
โ Scribed by Yasuhisa Matsui; Daiji Okamura
- Publisher
- John Wiley and Sons
- Year
- 2005
- Tongue
- English
- Weight
- 323 KB
- Volume
- 27
- Category
- Article
- ISSN
- 0265-9247
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โฆ Synopsis
The mode and timing of germ-cell specification has been studied in diverse organisms, however, the molecular mechanism regulating germ-cell-fate determination remains to be elucidated. In some model organisms, maternal germ-cell determinants play a key role. In mouse embryos, some germ-line-specific gene products exist as maternal molecules and play critical roles in a pluripotential cell population at preimplantation stages. From those cells, primordial germ cells (PGCs) are specified by extracellular signaling mediated by tissue, as well as cell-cell interaction during gastrulation. Thus, establishment of germ-cell lineage in mammalian embryos appears to be regulated by a multistep process, including formation and maintenance of a pluripotential cell population, as well as specification of PGCs. PGCs can be generated from pluripotential embryonic stem (ES) cells in a simple monolayer culture in which tissue interaction does not occur. This raises the possibility that ES cells, as well as, possibly, pluripotential cells in preimplantation embryos, are more closely related to the PGC precursors than pluripotential cells after implantation. BioEssays 27: 136-143, 2005.
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