Theoretically, in vitro fertilisation could be performed by collecting the contents from a woman's fallopian tubes or uterus after natural ovulation, mixing it with sperm, and reinserting the fertilised ova into the uterus.
Upstream operations deal primarily with the exploration stages of the oil and gas industry, with upstream firms taking the first steps to first locate, test and drill for oil and gas. Later, once reserves are proven, upstream firms will extract any oil and gas from the reserve.
Downstream operations are oil and gas operations that take place after the production phase, through to the point of sale. Downstream operations can include refining crude oil and distributing the byproducts, such as gasoline, natural gas liquids, diesel and a variety of other energy sources, down to the retail level. The closer an oil and gas company is to the process of providing consumers with petroleum products, the further downstream the company is said to be.