Images Dated 1st June 1992

Neurons By Brightfield Microscope

Photomicrograph neurons. Light microscope. Neurons are the basic anatomical and functional units of the nervous system. The human nervous system contains approximately 28 billion neurons, also called nerve cells. All neurons outside the central nervous system (and many within it) conduct impulses along hair-like cytoplasmic extensions, the nerve fibers or axons. The axons connecting your spinal cord to your foot can be as much as 1 m long. Axons grow out of the cell body, which houses the nucleus as well as other organelles such as the endoplasmic reticulum. The length of some axons is so great that it is remarkable that the cell body controls them all the way to their tip. There is a steady transport of cell components from the cell body along the entire length of the axon. This flow is driven by kinesins moving along the many microtubules in the cytoplasm within the axon. Even so, it may take 2 weeks or longer for material synthesized in the cell body to reach the axon terminals in your ankle or toes. Magnification unknown

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