Hi Alvin and Etherfish:
Actually, the bladder plays a key role in the circulation of sexual essences, which corresponds with the pranic flow. Every pranic flow has a neurobiological correspondence. Which is not to say we can always pin-point it, because as it refines it runs deep into the ecstatic realms and marries with pure bliss consciousness which underlies the whole process. Kind of hard to find the bladder, or any other body part, in there.
None of this is to say that we ought to be having lots of orgasms and blocking them up into the bladder. No. What happens is, over the course of our development on
all fronts in yoga in relation to our normal life (including normal sexual activity redirected via tantric means), a very refined process develops which involves sexual essences being drawn up through multiple pathways -- the bladder being but one of them, the one most associated with spiritual arousal and flow of the subtle (or not so subtle) sexual essences. This applies to both women and men, though there are differences in method due to anatomy, of course.
After writing this morning, I thought of an analogy that might help with understanding the natural versus not-so-natural approaches that men take to this in relation to vajroli:
If we want to keep the horse in the barn, does it make sense to be letting the horse out of the barn and then devising complicated strategies (macho vajroli) for getting the horse back into the barn? Maybe it would be better to put a good latch on the barn (blocking) and then the problem is solved.
There are those who would say, "Don't go near the barn (abstention), and the horse won't be getting excited and trying to run out."
Maybe so, but that leaves the horse either irritated or asleep, neither of which is tantric or yogic. So we actively engage the horse, teaching it to be active in the barn. Then we find vast new directions the horse can run without ever leaving the barn. Well, am I taking this analogy too far?
Remember, the definition of brahmacharya (from the AYP point of view) is both "preservation and cultivation of sexual energy." That is why we do the practices we do in AYP.
And yes, Alvin, a little inner experience goes a long way toward verifying what is being said here. Otherwise, we'd be wasting our time. Experience is the final arbiter in all of this, and enables us to proceed with confidence in self-directed practices.
For making more progress, you can also add mulabandha and/or asvini into the mix. Take your pick -- both are mainly in the anus/rectum in AYP and from there it naturally goes where it must.
The biggest stimulator of prana in the pelvic region is kumbhaka (breath retention as found in yoni mudra and chin pump), but I suggest you not take that on until you are very stable in everything that comes before. Spinal breathing has a more gentle kumbhaka effect, so that is the place to tackle it with breath first. Pranayama (restraint of breath) is the single greatest stimulant of ecstatic conductivity. When combined with siddhasana and mulabandha and followed by deep meditation, we can't miss over the long term. And that is without even considering tantric sex -- which makes a poor spiritual practice all by itself. There are too many other aspects that have to be addressed to achieve ecstatic conductivity. Tantric sex alone cannot do it. So don’t get too carried away with the tantra thing. Keep your practices in balance.
And enjoy!
The guru is in you.