The human sperm is composed of a head and a tail, the tail being divisible into a neck, a middle piece, a principal piece, and an end piece; the head, 4-6 mcm in length, is a broadly oval, flattened body containing the nucleus; the tail is about 55 mcm in length. Synonym(s): sperm cell, spermatozoon. [G. sperma, seed]
Switzerland is the 15th largest export economy in the world. In 2016, Switzerland exported $302B and imported $268B, resulting in a positive trade balance of $34.7B. In 2016 the GDP of Switzerland was $659B and its GDP per capita was $62.9k. The top exports of Switzerland are Gold ($82.1B), Packaged Medicaments ($39.7B), Human or Animal Blood ($26.2B), Base Metal Watches ($12.1B) and Jewellery ($10.8B), using the 1992 revision of the HS (Harmonized System) classification.
The United States is the world's largest economy with a GDP of approximately $18.56 trillion, notably due to high average incomes, a large population, capital investment, moderate unemployment, high consumer spending, a relatively young population, and technological innovation.