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An ovum or egg is gamete/germ cell which is released from either of the female reproductive organs, the ovaries during ovulation. Each egg is haploid therefore contains half the genetic information (one set of chromosomes) and is capable of developing into a new organism when fertilised with a sperm cell during sexual reproduction to form a zygote. Also each egg is genetically different due to meiosis.

The outer surface of each ovary is covered by a layer of cells (germinal epithelium); these surround the immature egg cells. A hollow ball of cells, the follicle. Within the follicle the immature ovum forms - an oocyte. Oocytes are present in a femle from foetal stage. When sexual maturity is reached the oocyte undergoes a meiotic division and becomes a mature egg, ready to be released. This process is called oogenesis.


  1. p546-563 Molecular Biology of the cell 5th ed. 2008 Alberts, Johnson, Lewis, Raff, Roberts, Walter

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