How can you clone a mouse? - briefly
«Mouse cloning» is achieved by transferring a donor somatic‑cell nucleus into an enucleated oocyte, stimulating embryonic development, and implanting the embryo into a surrogate mother. The offspring produced is genetically identical to the original animal.
How can you clone a mouse? - in detail
Mouse cloning relies on somatic cell nuclear transfer (SCNT) and embryonic stem cell (ESC) techniques. The procedure can be divided into distinct phases: donor cell preparation, enucleation, nuclear transfer, embryo culture, and implantation.
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Selection of donor tissue
• Adult fibroblasts or embryonic cells harvested under sterile conditions.
• Cells cultured to achieve a synchronized cell cycle, typically in the G0/G1 phase. -
Oocyte collection and enucleation
• Mature oocytes retrieved from super‑ovulated female mice.
• Micromanipulation removes the meiotic spindle and associated chromosomes, leaving a cytoplast ready to receive a nucleus. -
Nuclear transfer
• A single donor nucleus introduced into the enucleated oocyte by electrofusion or direct injection.
• Fusion medium contains calcium ions and a brief electric pulse to promote membrane merging. -
Activation and early development
• Chemical agents (e.g., strontium chloride) or electrical stimuli trigger embryonic activation.
• Embryos cultured in KSOM medium at 37 °C, 5 % CO₂, monitored until the blastocyst stage (≈3–4 days). -
Embryo transfer
• Viable blastocysts surgically implanted into the uterine horns of pseudopregnant surrogate females.
• Pregnancy progresses to term; offspring are screened for genetic identity using microsatellite analysis or whole‑genome sequencing.
Critical considerations include:
• Genetic integrity of donor cells, requiring minimal passage number to avoid mutations.
• Cytoplasmic quality of recipient oocytes, influencing reprogramming efficiency.
• Optimization of activation protocols to enhance developmental competence.
• Ethical compliance with institutional and national regulations governing animal cloning.
Success rates remain low, typically 1–5 % of transferred embryos resulting in live births. Continuous improvements in epigenetic reprogramming and culture conditions aim to increase efficiency and reproducibility of mouse cloning.