Cross-section of a peripheral nerve (200X)

The image on the left is not a collection of soap bubbles on a kitchen sink but a cross-section of a peripheral nerve. A nerve is a bundle of nerve fibers that transmit signals between the body and the central nervous system (CNS).

Once again, there’s not much to showcase here, so there won’t be a quiz for this section. However, if you click through the arrows, there are still a few interesting structures to examine.

As you can see, there are several groups of dark elements encapsulated in a light brown material. The dark structures are nerve fiber bundles, or fascicles. The fascicles are composed of axons and their supporting tissues. Closest to the axons are the Schwann cells, which are themselves surrounded by loose vascular connective tissue called the endoneurium.

Around each fascicle, there are two layers of connective tissue: the perineurium (surrounding each individual fascicle) and the epineurium (binding multiple fascicles together). On the following pages, you’ll learn more about these structures.