Expression of Trp53 mRNA within preimplantation stage embryos. RTPCR was performed with specific primers to detect β-Actin (positive control) or Trp53. The negative control (No RT) – Trp53 primers but no reverse transcriptase. 1. liver mRNA positive control, 2. oocytes. 3. zygotes. 4. early 2-cell stage. 5. late 2-cell stage, 6. morulae, and 7. blastocyst. Each analysis was performed on groups of 20 embryos and results are representative of 4 replicates.