Deep dorsal vein of clitoris

Transcription

My field of study is anatomy. I teach pathology, as it happens, but anatomy is my training. And my interest is because New Zealand had a very high rate of circumcision. And it seemed to be a very anomalous practice to me personally and collectively. So I got a bit curious as most boys do as to why this was happening. And I began studying it quite early in my life as it happened. And the more I looked into it the more anomalous and senseless it seemed to be. It didn't seem to have a medical purpose to it is the best way to put it. So that is the background to my studies. Well we have to use histological methods. Now, histology is a branch of pathology which looks at tissue in its natural form. It comes from the Greek meaning a web or net or fabric. And so you slice tissue up into very thin slices, put them on slides and look at them under the microscope to interpret the architecture of the cells, how they're lined up. Most people are familiar with the general picture of how the skin is arranged and so on. And that's how it's done. You have to then take the two-dimensional images that you see on the microscope and build up a three-dimensional image of it. Things have progressed, of course, considerably in recent years. We can now using computer technology and confocal microscopes -- you need another microscope to do that -- and build absolutely exquisite three-dimensional pictures of tissues. Well, the thing that struck me about it was the similarity with the fingertip with the high level of innervation, lots of sensory tissue. And the fact that it was far more complicated than just a simple extension of the shaft skin of the penis which is what most people say it is, that it's a flap extended over the glans to protect the glans. It is not. I would regard it as an organ in its own right because it has at least two major functions. The first function is mechanical. It provides a rolling bearing on the penis which you wouldn't have otherwise. It also provides the extra tissue required for expansion, changes in size. The penis does get bigger and if the skin was of a fixed size then a good deal of discomfort would result from a huge amount of stretching to accommodate the doubling in size that occurs with erection. So the foreskin provides, accommodation is the word we would use to describe changes in size. The second major function is the sensory function. It has become very evident to us over the last 15 years or so when John Taylor and his team came out with the findings in the early 1990s that the realization has come upon us even if people didn't stop to think about what they were feeling themselves if they were intact. I certainly didn't, I didn't really sit down to analyze what I was feeling but the microscope disclosed to us that the foreskin is heavily sensory in its function. It is my belief that it has the highest concentration of sensory nerve endings anywhere on the male body. So, it can't be described as a simple piece of skin. Males and females develop from the same embryological tissue. They have two possible pathways that that tissue can develop in. And males go down one path under the influence of testosterone. And females go down the other without testosterone. And, yes, most embryologists would say that there are distinct analogs between the two. The labial tissues, for instance, are said to be the analog of the scrotum. And, of course, the penis itself has its analog in the clitoris. The foreskin has its analog also in the female. There is a female foreskin, the clitoral hood. The difference is, and this is one of the mysteries of anatomy, is that the male has the nerve endings arranged differently in the female to the male. And it is the human male that is extraordinarily unique. We do not even have the same arrangement as other primates. Chimpanzees, for instance, our nearest cousins, if you will, do not have the same nerve arrangement on the penis that we do. It's the reverse, in fact. So humans have developed a penis that's utterly unique. And the thing that fascinates me is that it's been done in such a short period of time. About four and a half to five million years of evolution, which is but in a blink of an eye. So, there are great mysteries with the human penis. The specialized sensory tissue that I have been describing is really quite fascinating. The skin of the penis is zipped up just like an ordinary zip on the underside as the layers of cells develop in the embryo. And that, recall the raphe, that little line, the seam that goes up and at the top of the penis it becomes the little bridge, the frenulum, which is latin meaning a little bridle actually. Frenum is a bridle, a horses bridle. And a frenulum is a little bridle. And that tethers the foreskin onto the base of the glans on the underside. Now, for many years people thought that that was the only real specialization that had occurred, that it was a leftover of this process of zipping all the skin up as it was developed. But now we realize that this amazing concentration of nerve endings is related to that frenulum and from the frenulum draping away to each side is a band of ridges, folds, in the skin, which John Taylor has called the Ridged Band. There are about eleven or twelve ridges and they are very similar to the ridges on the fingertip and they run right round the entire diameter of the penis and rise up into the frenulum. And they enclose in the inner foreskin a delta, a triangle of skin which we've called the frenular delta, below the frenulum which is exquisitely innervated and most men know this as their own G-spot, the spot that is most sensitive area of the penis. In that area, in the ridged band and in the frenular delta we have the same specialist nerve endings that we have in the fingertip. Only we have probably ten times as many, I would believe. The number hasn't been accurately counted yet but the number of nerve bundles that wire them up is known and it's very impressive. So the foreskin is undoubtedly the main sensory unit of the penis. When it is removed, you remove at least 50% of the sensory capacity, so the effect is devastating to the sexual capacity of the organ, as has been well known for centuries. So it's a fascinating organ from the neurological point of view. And this arrangement, this specialized arrangement, is why you cannot regard the foreskin as just ordinary skin. It isn't. It's highly specialized. And, therefore, because of the two functions that I've mentioned, it is an organ in its own right. Well, circumcision, by its very nature, not only removes 50% of the skin of the penis, because 50% of the skin is involved in the foreskin. It's a substantial piece of skin. It's the size of an index card effectively in the adult. And that amount of skin, that is removed includes all of the ridged band and most of the frenular delta. The frenulum may or may not be removed. Some surgeons believe its a nuisance and should be extirpated as they say, wiped out, and others would leave it alone. And those that leave it alone, leave some of the frenular delta behind and therefore some of the G-spot. But those that completely destroy it take away all of the specialized sensory tissue. Now that large number of nerve bundles that supply those nerve endings are cut through and then you would have the standard response of cut axons, or wires, in the neurosystem and the sensory neurons, their cell bodies which are at the position on the cord, they're at the cord itself, the spinal cord, they then have to try and do some sort of damage control. If you cut an area of your skin and you cut through some nerve bundles, then the nerve cells will attempt to rebridge and go back to where they were originally and there's a well known, well characterized process for that happening. And they will send out growth cones from the stump and seek where they were originally connected. The downstream portion of the nerve from the cut will, of course, be disconnected from the cell, and therefore from its support and it becomes becomes necrotic and it is cleaned up by the immune system and taken away. Now, in the case of something like the foreskin, where you have chopped out a major piece of skin, the target area with the nerve endings that those wires, the axons, had originally gone to have now been removed. So they cannot find where their original endpoint was. So the growth cones go out, they come up against the scar tissue which they cannot penetrate and they then either die back completely or they get into a knot of growth cones and all that can transmit is pain. And they're known as pain neuroma of scar tissue. Now, circumcision removes 50% of the skin of the penis and unfortunately the most important part of the skin, the functional end, not the base where it doesn't matter. And it also removes something greater than 50% of the sensory nerve endings because they're concentrated in the frenular band and delta which is automatically destroyed in circumcision. We're probably safer to think that its probably closer to 75, 80% of the sensory tissue is lost. Now, the functional effect of that is, that the sensory drive into the spinal cord and up into the central nervous system is then greatly reduced. So, not only does the man not feel too much sensation, and there's a friend and colleague, of mine who says many circumcised men do not know where their orgasm is. They cannot -- they don't have enough pre-orgasmic sensation to know how the rise of sensation is proceeding and an orgasm in many of these men comes upon them by surprise, more or less. And then the pain and temperature -- the very simple protective and rather unpleasant sensation that comes from the glans when it's at rest is turned off by this drive from the foreskin because of inhibitory interneurons in the spinal cord. So that, in other words, when you have enough cascade of sensation driving into the cord it sets off inhibitory interneurons which turn off and inhibit the input from the glans. So men don't feel anything from their glans because they wouldn't want to. So what happens then in the circumcised man? When orgasm occurs and the foreskin sensory drive begins to tail off there isn't enough of it -- there's less than 50% of it, of course -- there isn't enough of it to maintain the inhibition of the glans. And suddenly they feel the most unpleasant sensation of the glans and they want an instant stop of motion. They've either withdrawn from their female partner or if they're still inserted, they say "For heaven's sake, stop. Don't move. You know, I can't bear it." And this is a very common feature in circumcised men. And it must be devastating for their partners to suddenly have this disconnect of what should be the most joyous moment. And it's always been a difficulty for me to understand exactly what's been going on but this is how we believe. There's a term for it, dyspareunia, is one of the terms, pain, pain of intercourse. And it's almost invariably confined to circumcised men. It does appear in intact men, when the foreskin is not as mobile as it should be, they get it a bit tangled up. When they're saying that, they're talking of the sensation that's coming from the glans. And the glans does not have the neural equipment to send fine touch, what we call 'fine touch' sensation. It only sends through nerve ending sensation… In fact, the nearest equivalent is the corner of the eye. You don't like stroking the corner of the eye at all. But if you have an eyelash get under the eyelid, you know it's there but you don't know exactly where it is. And it's dreadfully upsetting and you want to go and get it cleared. That is what the glans produces. You don't know exactly where it is because it's not a high-resolution system but it's very unpleasant and that gets turned off when the man is in the pre-ejaculatory or pre-orgasmic phase. So, we've got a mechanism in other words in normal, intact men for taking away this protective sensation when you don't need it -- during sexual intercourse. But in circumcised men it returns at the wrong moment. Well, the natural end of this to avoid nerve damage, and the loss of sensation and a lifetime of erotic pleasure, and the avoidance of this peculiar pain effect, is to not to cut them in the first place, just leave it alone. Of course, evolution has actually figured the right pathway. Boys are being born every minute and second of the day complete with foreskins. And they're going to continue to be born with foreskins.