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After a vasectomy, it takes about 12 ejaculations to clear out sperm that were already beyond the blocked area.
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.
The Babylonians wrote numbers in a system that used 60 as the base value rather than the number 10. They did not have a symbol for "zero."
Ether was used widely for surgeries but became less popular because of its flammability and its tendency to cause vomiting. In England, it was quickly replaced by chloroform, but this agent caused many deaths and lost popularity.
More than 2,500 barbiturates have been synthesized. At the height of their popularity, about 50 were marketed for human use.