PROFESSORS P.M. MOTTA & S. MAKABE / SCIENCE PHOTO LIBRARY PROFESSORS P.M. MOTTA & S. MAKABE / SCIENCE PHOTO LIBRARY
Egg cells. Coloured scanning electron micrograph of the surface of an ovary of a human embryo 9 weeks after fertilisation. Three primordial egg or germ cells (red), called oogonia, are surrounded by epithelial cells (green); the germ cells have migrated from the yolk sac into the ovarian cortex by using the amoeboid evaginations (top centre left) on their surface. Once in the ovary they multiply by mitosis and by the fourth and fifth months of foetal development they number about 7 million. Only 1 million will be present at birth and will represent the patrimony of eggs in the woman's ovary. Magnification: x2300 at 6x7cm size.
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