Steroid hormones are not stored prior to release and so must be synthesized de novo upon each new stimulus.
The precursor of all steroids is cholesterol which can be manufactured at most sites; the placenta is the exception, needing to absorb cholesterol from the blood prior to steroid biosynthesis.
In terms of the sex steroids, progestagens are precursors for androgens which are precusors for oestrogens.
This section is considered in terms of:
Last reviewed 01/2018