When does an egg cease to be an egg?

At which point does an egg cease to be an egg?

Mystery Hour Question

At which point does an egg cease to be an egg?

Andy, Canterbury

Answer

** Definitive **
Name: Professor Howe, University of Brighton
Qualification: Professor of the Public Understanding of Science
Answer: A human egg has got 23 chromosomes which is called a haploid number which is half the number of chromosomes (in a human). Once an egg becomes fertilised by a sperm it becomes a diploid number (46 chromosomes). At that point it ceases to be an egg. At the moment of fertilisation it becomes a zygote. Which then turns into an embryo which the turns into a baby. We can do the exact same analogy with chickens’ eggs. The moment it’s fertilised it’s no longer an egg, it’s a zygote. As soon as the haploid number becomes diploid, it’s no longer an egg.