The nerve fibres there figured are bound together by endoneurium into small ropes, the nerves, encased in perineurium.    From Wordnik.com.  [Text Book of Biology, Part 1: Vertebrata] Reference

It is continuous with septa which pass inward from the innermost layer of the perineurium, and shows a ground substance in which are imbedded fine bundles of fibrous connective tissue running for the most part longitudinally.    From Wordnik.com.  [IX. Neurology. 1. Structure of the Nervous System] Reference

The tubular sheath of the funiculi (perineurium) is a fine, smooth, transparent membrane, which may be easily separated, in the form of a tube, from the fibers it encloses; in structure it is made up of connective tissue, which has a distinctly lamellar arrangement.    From Wordnik.com.  [IX. Neurology. 1. Structure of the Nervous System] Reference

Each ganglion is invested by a smooth and firm, closely adhering, membranous envelope, consisting of dense areolar tissue; this sheath is continuous with the perineurium of the nerves, and sends numerous processes into the interior to support the bloodvessels supplying the substance of the ganglion.    From Wordnik.com.  [IX. Neurology. 1. Structure of the Nervous System] Reference

The bloodvessels supplying a nerve end in a minute capillary plexus, the vessels composing which pierce the perineurium, and run, for the most part, parallel with the fibers; they are connected together by short, transverse vessels, forming narrow, oblong meshes, similar to the capillary system of muscle.    From Wordnik.com.  [IX. Neurology. 1. Structure of the Nervous System] Reference

Covering of fiber bundle, or perineurium.    From Wordnik.com.  [Physiology and Hygiene for Secondary Schools] Reference