Final answer:
The sagittal suture typically begins to close late in life, with the process varying among individuals. It is a key part of cranial development, allowing the brain and skull to grow after birth until it ossifies and the bones fuse significantly in adulthood.
Step-by-step explanation:
The approximate age at which the sagittal suture closes can vary, but it generally begins to ossify and fuse causing the suture line to gradually disappear late in life. The process of sutural closure is part of normal skull development. The sagittal suture extends along the midline at the top of the skull, uniting the right and left parietal bones. The ossification of cranial sutures, such as the sagittal, coronal, and lambdoid, can lead to a condition known as synostosis when it happens early in life, which is the fusion between bones. This premature closure can cause a condition known as craniosynostosis, affecting the shape of the head and potentially impairing brain growth. However, the timing of suture closure can vary widely among individuals.
During birth, wide areas of connective tissue known as fontanelles provide flexibility to the skull. The fontanelles and sutures allow for the rapid growth of the skull and brain after birth. The anterior fontanel, for instance, tends to close within the first nine to 18 months after birth. As the connective tissue ossifies over time, sutures such as the sagittal suture will close, with significant closure often observable in adulthood and continuing as part of the aging process.