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Apoptosis in the early bovine embryo
C Matwee1, D H Betts, W A King
1Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Canada.
Zygote (Cambridge, England)
|June 7, 2000
Summary
Apoptosis, or programmed cell death, occurs in bovine embryos, increasing with developmental stage. This suggests embryos can better manage abnormal cells as they grow.
Area of Science:
- Reproductive Biology
- Developmental Biology
- Cell Biology
Background:
- Cell death is observed during early embryonic development, but its mechanisms and relation to embryonic loss remain unclear.
- Apoptosis is a distinct form of cell death characterized by specific morphological and molecular features, contrasting with necrosis.
Purpose of the Study:
- To investigate the occurrence and developmental stage-dependency of apoptosis in bovine oocytes and in vitro fertilized embryos.
- To explore the potential involvement of the p53 tumor suppressor gene in bovine embryonic apoptosis.
Main Methods:
- Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay for DNA fragmentation.
- Morphological assessment for apoptotic features.
- Reverse transcription polymerase chain reaction and whole-mount immunofluorescence for p53 expression and localization.
Main Results:
- TUNEL labeling, indicative of apoptosis, was detected in immature oocytes, mature oocytes, and advanced stage embryos (morulae/blastocysts), but not in zygotes or early cleavage-stage embryos.
- Apoptosis could be induced in early cleavage-stage embryos using staurosporine treatment.
- While p53 transcripts were present, nuclear localization of p53 protein was not detected in blastocysts, suggesting p53-independent apoptosis.
Conclusions:
- Apoptosis in bovine embryos is dependent on the developmental stage under standard culture conditions.
- Bovine embryos appear to develop a greater capacity to accommodate damaged or abnormal cells as development progresses.