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When do the major folds and grooves of the human brain develop before birth?
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human development
Growth of the human fetus from the fourth month to the ninth month of pregnancy.
The development of the major folds and grooves of the human brain, known as gyri and sulci, occurs during the fetal period of prenatal development.1
While the main outlines of the brain are recognizable by the end of the third fetal month, the formation of these convolutions follows a specific timeline:
- Fifth fetal month: The central and calcarine sulci become discernible.1
- Seventh month: All major gyri and sulci are normally present.1
It is important to note that while the major structures are established before birth, many minor sulci and gyri continue to appear during the postnatal period.1