Pregnane

Pregnane, also known as 17β-ethylandrostane or as 10β,13β-dimethyl-17β-ethylgonane, is a C21 steroid and, indirectly, a parent of progesterone. It is a parent hydrocarbon for two series of steroids stemming from 5α-pregnane and 5β-pregnane. It has a gonane core.
5β-Pregnane is the parent of pregnanediones, pregnanolones, and pregnanediols, and is found largely in urine as a metabolic product of 5β-pregnane compounds.

Pregnanes

Image:Steroid numbering.svg|thumb|260px|class=skin-invert-image|Steroid nomenclature: Pregnanes have carbons 1 through 21.
Pregnanes are steroid derivatives with carbons present at positions 1 through 21.
Most biologically significant pregnane derivatives fall into one of two groups: pregnenes and pregnadienes. Another class is pregnatrienes.

Image:Cortisone structure.png|thumb|260px|class=skin-invert-image|Cortisone
Pregnenes have a double bond. Examples include:

Image:Cyproterone_acetate.svg|thumb|260px|class=skin-invert-image|Cyproterone acetate
Pregnadienes have two double bonds. Examples include: