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Hypoxic microenvironment within an embryo induces apoptosis and is essential for proper morphological development
E Y Chen1, M Fujinaga, A J Giaccia
1Mayer Cancer Biology Research Laboratory, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305-5468, USA.
Teratology
|October 6, 1999
Summary
Hypoxia (low oxygen) is present in developing rat embryos and influences development. Manipulating oxygen levels impacts embryonic morphology and cell death, highlighting the interplay between genetic programs and the microenvironment.
Area of Science:
- Developmental biology
- Embryology
- Physiology
Background:
- Hypoxia-inducible transcription factors are implicated in development.
- The in vivo existence and role of embryonic hypoxia remain unclear.
Purpose of the Study:
- To investigate the presence and role of hypoxia in embryonic development.
- To determine how oxygen levels affect embryonic morphology and cell death.
Main Methods:
- Culturing rat embryos in utero at gestational day 11.
- Exposing embryos to varying oxygen concentrations (45% and 5%) from gestational day 9-11.
- Assessing morphological development and cell death (apoptosis).
Main Results:
- Hypoxic regions identified in gestational day 11 rat embryos (hindbrain, otic vesicle, first branchial arch).
- High oxygen (45%) caused morphological abnormalities (neural tube defects, abnormal otic invagination, somite defects) and reduced cell death.
- Low oxygen (5%) resulted in stunted growth but normal morphology, with increased apoptosis.
Conclusions:
- Embryonic development is influenced by the oxygen microenvironment.
- Normal development requires an interplay between genetic programs and environmental cues, such as hypoxia.
- Hypoxia plays a role in activating apoptotic cell death during embryogenesis.