Biosynthesis of Basic Steroidal Structure

The conversion of cycloartenol (20) (which appears to act only as an intermediate) to functional end products involves oxidative (O2, NADPH) removal of the three methyl groups at C-4 and C-14, addition (frequently) of one or two car- 

All of the sterol in a photosynthetic plant is derived by biosynthesis de novo in that plant, but neither the contribution of the various tissues to the total biosynthetic pool nor the role of transport (41, 64) is well investigated. It is not known, for instance, how much of the sterol of wood or bark actually is biosynthesized in the stem itself or is biosynthesized in the leaves and then carried to the stem. 

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