zona fasiculata and zona reticularis biosynthesis

Last reviewed 06/2022

The zona fasiculata and reticularis have the enzyme 17-alpha-hydroxylase, which 17-hydroxylates pregnenolone and progesterone.

These 17-hydroxy steroid can then be metabolised as follows:

  • to 11-deoxycortisol, catalysed by 21 beta-hydroxylase
  • to cortisol, by 11 beta-hydroxylase

Alternatively a further reaction, catalysed by 17,20 lyase can convert the 17-hydroxysteroid to the sex hormone precursors.