Meninges: Embryology

The adult central nervous system (CNS) is largely encased by three concentric connective layers named dura mater, arachnoid, and pia mater. They constitute a fibrous envelope, which provides for mechanical protection of the nervous system and participates in formation of the blood-brain barrier. The embryogenesis of the meninges varies across vertebrate species. The human meningeal development is still a matter of great controversy. Although comparative embryologic and anatomic studies have demonstrated that main developmental landmarks are conserved among the species, these findings should be cautiously extrapolated to the human embryonic development (1). Detailed studies on the embryogenesis of the meninges in humans by O'Rahilly and Müller in the late 1980s (2) presented the most comprehensive analysis yet on this complex issue. In this chapter I will provide a review of the development of the cranial and spinal human meninges and their correlation with the morphologic aspects of the adult meninges.