|MadSci Network: Development|
Greetings Christy, I noticed your previous question and the answer posted, so I will try and just answer your question without giving more of the same background material. Iris color is dependent on the relative number of granules of melanin within the melanocytes in the outer stroma of the iris. In adults, blue irises have <10 granules per cell, whereas very dark brown eyes can have <400. Caucasian infants tend to be born with blue or gray irises, whereas African American, latin and asian infants usually have brown-gray eyes. The developmental timeline is slightly different depending on the endpoint color. Children who will have dark colored eyes start their color change by 2 months of age, whereas those with lighter colored eyes typically start later, at about 5-6 months of age. Usually the color is close to the final adult color by about 6 months of age. However, male children sometimes undergo a color shifting to more mixed iris color in puberty, followed by a darkening and return to the ealier childhood color.
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