Micro Propagation works the same way with marijuana as it does with any other plant (woody plant species). it's the process of plant multiplication in vitro, to preserve plant genetics. where you take a sterilized cutting and place it in a specific culture medium. culture medium consists of inorganic and organic salts...micro and macro nutrients, sucrose, and you need growth regulators and something to gel the medium. if everything is properly balanced then the tip begins to elongate. when growth starts, shoots will be produced on the stem piece. There should be a rapid proliferation of shoots that will result in masses of shoots produced from 1 single shoot tip. I've heard that up to something like 100 shoots may be produced from 1 tip in like 10-12 weeks which can cloned, and the small plantlets can be placed in new sterile medium to continue your Micro Propagation,
!NOTICE! - it's extremely difficult to do tissue culture propagation without a lab or adequate equipment.
and this is all varied by the myriad of factors that come into play, and I've come to find theres a lot of chemistry involved, and so many things that could go wrong, so do your fair share of research and kno what you're doing before you try micropropagation.