Breasts start to form very early, during fetal development inside the uterus.
Here's a breakdown:
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Early Development: According to the reference material, breast development begins while the fetus is still growing in the uterus.
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Mammary Ridge: This initial development starts with a thickening in the chest area called the mammary ridge or milk line.
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Nipple and Ducts: By the time a baby girl is born, nipples and the beginnings of the milk-duct system have already formed.
Therefore, breast development begins prenatally, with the formation of the mammary ridge and the beginnings of the milk-duct system.
