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Human neurons are so small that they require a microscope in order to be seen. However, some neurons can be up to 3 feet long, such as those that extend from the spinal cord to the toes.
Many medications that are used to treat infertility are injected subcutaneously. This is easy to do using the anterior abdomen as the site of injection but avoiding the area directly around the belly button.
About 3% of all pregnant women will give birth to twins, which is an increase in rate of nearly 60% since the early 1980s.
There are 20 feet of blood vessels in each square inch of human skin.
The tallest man ever known was Robert Wadlow, an American, who reached the height of 8 feet 11 inches. He died at age 26 years from an infection caused by the immense weight of his body (491 pounds) and the stress on his leg bones and muscles.
![In the summer of 1793, a yellow fever epidemic struck Philadelphia, killing nearly 4,000. Tens of th](https://biology-forums.com/gallery/47/medium_374628_16_08_15_9_52_07_222511109.jpeg)
![On March 25, 1911, as scores of young factory girls leaped to their deaths from the eighth, ninth, a](https://biology-forums.com/gallery/47/medium_376716_26_08_15_11_19_27_22455374.jpeg)