Final answer:
The arachnoid mater is the meninx made of simple squamous epithelium and a fiber mesh. Simple squamous epithelium is composed of a single layer of flat cells and is found in areas needing rapid chemical transport, such as lungs and blood vessels.
Step-by-step explanation:
The meninx that consists of simple squamous epithelium with a mesh of fibers in the adjoining space is the arachnoid mater, which is one of the three layers of meninges surrounding the brain and spinal cord.
Simple squamous epithelium is a single layer of flat, scale-like cells that promote diffusion and filtration across their surface. This epithelial tissue can be found in locations where rapid passage of chemical compounds is necessary, such as the alveoli of lungs, segments of kidney tubules, the lining of capillaries, and as the endothelium of lymphatic and cardiovascular vessels. The mesothelium, which is also composed of simple squamous epithelial cells, forms the surface layer of the serous membrane lining body cavities and internal organs, providing a smooth and protective surface that secretes lubricating fluid.