Expected headings
"Related pathology"
"The structure appears between the 3rd and 5th week of gestation and differentiate into the arachnoid mater, pia mater and dura mater by the end of the first trimester 3. The dura, arachnoid and outer pia mater is of mesodermal origin, while the inner layer of the pia mater is of neuroectodermal origin."