Phantastica, the experiment failed. The required sterile conditions were not met and fungi rapidly took over the growing medium. Furthermore, the growing medium wasn't appropriate since it lacked several of the crucial components, so nothing would have grown anyway. I'm not being pessimist; one really has to do it correctly or not do it.

The good news is that I have studied micropropagation from books now, so things will not be improvised in future experiments. The needed sterilization equipment and components for the growing medium have been gathered. I'm positive that this new experiment will be successful and that we will have a solid technique for propagating cacti in-vitro soon.

I'm as excited as you are with this. It's very promising.