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Primordial germ cells in the mouse embryo during gastrulation
M Ginsburg1, M H Snow, A McLaren
1MRC Mammalian Development Unit, Wolfson House (University College London), UK.
Development (Cambridge, England)
|October 1, 1990
Summary
Researchers identified alkaline phosphatase-positive cells in early mouse embryos, suggesting these are primordial germ cells (PGCs) set aside at least by 7 days post coitum. This discovery pushes back the earliest known PGC lineage determination in mice.
Area of Science:
- Developmental Biology
- Cell Biology
- Embryology
Background:
- Primordial germ cells (PGCs) are the precursors to gametes.
- Identifying the earliest stages of PGC development is crucial for understanding germline formation.
- Previous studies have not identified PGCs as early as the primitive streak stage.
Purpose of the Study:
- To identify and characterize the earliest population of primordial germ cells (PGCs) in mouse embryos.
- To determine the developmental stage at which the PGC lineage is established.
- To investigate the initial differentiation markers of PGCs.
Main Methods:
- Whole-mount alkaline phosphatase (ALP) staining technique.
- Observation of mouse embryos at 7-7 1/4 days post coitum (dpc).
- Excision of specific embryonic tissue and subsequent culture to assess PGC presence.
Main Results:
- A distinct cluster of ALP-positive cells was detected in the extraembryonic mesoderm of 7-7 1/4 dpc embryos.
- These cells exhibited characteristics consistent with early PGCs, including an ALP-positive cytoplasmic spot.
- Removal of this cluster prevented PGC formation in cultured embryos, while the excised tissue was rich in PGCs.
- By 8 dpc, ALP-stained cells were found in the hindgut endoderm and allantois, aligning with known PGC locations.
Conclusions:
- The identified ALP-positive cell cluster represents primordial germ cells (PGCs) at a significantly earlier stage than previously reported.
- The PGC lineage in mice is established by at least 7 dpc, emerging as an early mesodermal cell type.
- The differentiation of PGCs, marked by ALP activity, is a gradual process.