Question

Which one of the following meninges is present only in mammalian brain?

• A. Dura mater
• B. Arachnoid
• C. Pia mater
• D. None of the above

Answer 1

The correct option is B Arachnoid

Surrounding the adult brain are layers of mesodermally-derived connective tissue, called as meninges. Whereas cyclostomes and fishes only have a single envelope called as the primitive meninx, amphibians have two layers, consisting of an outer dura mater, which is extremely dense and protective, and a pia-arachnoid or secondary meninx, which is more delicate and vascular. They do not have a separate arachnoid layer.

Mammals have three meninges: pia mater, the arachnoid layer (which is delicate and sends strands to the pia mater) and the dura mater (the outer, more protective meninx).