Answer:
arachnoid mater
Explanation:
CSF is gradually reabsorbed into the blood at the same rate at which it is formed to maintain the constant pressure. The arachnoid mater has finger-like extensions that project into the dural venous sinuses, especially the superior sagittal sinus. The projections of arachnoid mater are called arachnoid villi and a group of arachnoid villi is called an arachnoid granulation. Arachnoid villi are the structures through which cerebrospinal fluid is drained into the superior sagittal sinus and is reabsorbed into the bloodstream.
