Cerebral pia mater软脑膜 Closely invests brain surface. in some areas the pI 1a invaginates into ventricles to take part in the formation of choroids plexusCerebral pia mater 软脑膜 ◼ Closely invests brain surface, in some areas the pia invaginates into ventricles to take part in the formation of choroids plexus