Fr8tren, you migh want to rethink the statement that hyperplasia cannot occur in human... as for whether this happens w/ SEO's I am unsure. I'm not convinced that is what he was trying to say, though. Sounds more like hypertrophy- the SEO fills the fascia for a time, stretching it and the surrounding skin. When it dissipates, the existing muscle tissues/fibers enlarge (hypertrophy) to fill in the space left by the oil dissipating. This process occurs over an extended period of time, though. Don't get the idea that the oil will just drain out all of a sudden and the muscle will just expand to fill it. The collagen in the SEO's make it stick around for months. Like Big A said, that is the main (and really only) difference between site injections of oil based AAS, and SEO's.
While I've never used SEO's I can't vouch for there effectiveness other than the initial volumizing effects (i.e. whether the size is permanent/can be maintained after dissipation). It does make sense to me though that the muscle would work to fill in the area that was stretched given that the proper environment for growth (hormones, macronutrients, excercise, rest, etc...) is in place. I could see how the muscle would respond this way, similar to muscle memory when a person loses size and can gain back old muscle much more effeciently. The body would feel volume leaving, and go to replace it with the only thing it can - muscle protein. Just like AAS, I'm sure this principal wouldn't have a chance in hell without proper care taken to insure that the size stays after the oil leaves, but since it leaves so slowly I can see how it would offer an opportunity for increased growth at the site of the stretched fascia. My guess would be that you could maintain something like 50-75% of the size that the original oil occupied, but even that much could mean some serious gains.
I'm interested to hear from some people that have used SEO's for this purpose, and not simply to balloon up a muscle only to have to keep re-filling it to maintain its size.
I don't really fully understand the immense stigma that goes on with SEO's. Unlike most other size drugs/aids, incorrect use is painfully visible for all to see. Misuse of AAS, peptide hormones, and most all other drugs is completely internal and the mistakes aren't visible like bad SEO application, is one reason for the stigma. The use simply to "blow up" an area is another cause for this. Bodybuilders, unlike the general public, know that even performance enhancing drugs take an immense amount of work in order to exert maximum effects. While SEO's simply require a needle and the will to use in order to add some extra size is another cause.
The funny thing is people are only considered to be using SEO's if they are using them badly. When a person uses them correctly, you shouldn't be able to tell (other than maybe some quick growth if you know the individual). I personally wouldn't have a problem with sporadic use to get over a sticking point with specific muscles with the goal of filling in the oil with real muscle. The problem, or misuse, in my opinion is when use is ongoing and overdone (either too much in one site, or too many sites), where the user has no specific goal (ex. bringing up a specific part that's not responding) other than wanting to be bigger and doesn't want to put in the neccesary work.