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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.
Interferon was scarce and expensive until 1980, when the interferon gene was inserted into bacteria using recombinant DNA technology, allowing for mass cultivation and purification from bacterial cultures.
Egg cells are about the size of a grain of sand. They are formed inside of a female's ovaries before she is even born.
The toxic levels for lithium carbonate are close to the therapeutic levels. Signs of toxicity include fine hand tremor, polyuria, mild thirst, nausea, general discomfort, diarrhea, vomiting, drowsiness, muscular weakness, lack of coordination, ataxia, giddiness, tinnitus, and blurred vision.
The average adult has about 21 square feet of skin.