[Iguana]

This is a great article that was posted over at TP a while back. The entire article requires a paid subscription and no one ever posted the link. It's a very interesting study and could explain why some gain easily while some don't gain at all. Thought I would share it.



INTRODUCTION

The tunica albuginea of the penis lends great flexibility, rigidity and tissue strength to the penis [1]. It consists of an inner circular and an outer longitudinal layer [2]. Intracavernosal pillars arise from the inner layer and radiate into the corpora cavernosa (CC). Together with the septum, theyprovide support to the erectile tissue [3, 4]. The corpus spongiosum lacks the outer layer and the intracorporeal pillars [3].

The anatomical data regarding the origin, morphology, as well as nerve and blood supply of the bulbocavernosus muscle (BCM) and ischiocavernosus muscle (ICM), are well documented in the literature [5, 6, 7, 8]. However, the exact mode of insertion of these muscles into the TA of the penile shaft needs to be described more clearly. Detailed knowledge of the mode of attachment of the BC and IC muscle fibers into the penile TA seems necessary for a better understanding of the role of these muscles in the mechanism of erection. In the current communication, we studied the penile TA and the mode of insertion of the IC and BC muscles into it.

MATERIAL AND METHODS

The study was comprised of 28 cadaveric specimens: 18 adult (mean age 37.3 ± 8.6 SD years, range 26–48) and 10 fully mature neonatal cadavers. All the cadavers had normal genitourinary organs. The obtained specimens consisted of the perineum and included the penis with its bulb and crura and parts of the ischial tuberosities to allow for collection of the cavernosus muscles from origin to insertion. The specimens were fixed in 10% formalin. The TA and the mode of insertion of the cavernosus muscles into the penis were studied by the naked eye with the help of a magnifying loupe and bright light. Sections for microanatomical studies were then taken from the penile shaft and the root including the bulb and crura. The specimens were stained with hematoxylin, eosin and Verhoeff van Gieson stain. Each section was studied for the TA structure and the relation of the two cavernosus muscles to it.

RESULTS

In all 28 cases, the TA of the CC consisted of collagen fibers impregnated with few elastic fibers. The collagen fibers were arranged in bundles in a wavy pattern. In 20 cadaveric specimens, the TA of the CC was formed of two layers: an inner circular and an outer longitudinal (Figure 1). In six of the 28 specimens, it consisted of three layers: an inner circular, intermediate longitudinal and outer circular (Figure 2). In the remaining two specimens, the TA was formed of a single longitudinal layer (Figure 3). At the junction of the CC with the corpus spongiosum (CS) in all the studied specimens, the TA of the CC consisted only of the circular layer. The TA of the CS consisted of only one layer with circularly orientedfibers; no longitudinal fibers were detected in any of the specimens examined.

Mode of Insertion of the Bulbo-/Ischio-Cavernosus Muscles into the Tunica Albuginea

The BCM lay over the penile bulb and its muscle bundles were arranged in 3 groups: 2 lateral and 1 median (Figure 4). The lateral fibers were inserted into the perineal membrane. The median fibers were grouped together forming a ribbon that extended over the penile bulb and the proximal part of the CS, where it bifurcated into two limbs (Figure 4). Each limb proceeded laterally forward and approached the ICM at the lateral surface of each CC. The two muscles fused, forming one muscular limb, which, in 18 cadavers, ended in tendinous fibers that, together with the contralateral fibers, formed a fibrous belt over the dorsum of the 2 CCs. In 6/28 cadaveric specimens, the conjoint limb continued over the CC dorsum as fleshy fibers; it contained no tendinous fibers (Figure 5). In the remaining 4/28 specimens, the conjoint limb of the BCM and ICM was attached on each side to the lateral surface of the CC (Figure 6); no extension forming a belt over the dorsum of the CC was found.

DISCUSSION

The current study could shed some light on the structural-functional adaptation of both the TA and cavernosus muscles’ insertion to the erectile mechanism. The TA consisted mainly of collagen fibers that are inextensible. However, the wavy pattern of collagen in the flaccid state of the penis, as well as the impregnation of the TA with few elastic fibers, apparently give the TA a degree of expandability during erection.

Variations in the morphologic structure of the TA of the CC were detected. The two-layered TA was the most common with 71.4%, while the three-layered TA was encountered in 21.4% and the single layer in 7.2%. The exact significance of the structural variations of the TA during erection is not known. It is likely that the degree of tumescence depends on the TA structure. Thus, we assume that the triple-layered TA gives more firmness to penile erection than the single or double-layered TA. Similarly, the TA of 2 layers, which is the most common pattern, would provide a stronger erection than the single layer. This comparison of the role of the different layers of the TA in erection seems applicable, provided the other factors of penile erection are standardized. Alternatively, it might be that the increase of the TA layers impede the erectile process. On the other hand, the CS is covered by a single layer of TA, and this fact might diminish its rigidity on erection compared to the rigidity of the CC. However, the role of the different layers of the TA in erection needs to be investigated.

As regards to the mode of cavernosus muscles’ insertion into the TA, 3 patterns were encountered: fibrous belt, muscular belt and beltless. The fibrous belt insertion of the 2 cavernosus muscles was the most common pattern, representing 75% of the studied specimens. Meanwhile, the muscular belt occurred in 21.5% and the beltless type in 3.5%. The role of the different patterns of insertion of the conjoint cavernosus muscles in the TA is not known. The belt form, fibrous or fleshy, of cavernosus muscles’ insertion appears to be more efficient in compressing the CCs during erection than the beltless type. Furthermore, the fibrous belt apparently effects a firmer CC compression than the muscular belt. The role during erection, however, of the different patterns of cavernosus muscles insertion into the CCs needs to be studied further.

In conclusion, the TA occurred in three histomorphologic patterns: single, double and triple layers, the most common being the double-layered pattern. The different TA patterns are suggested to affect penile rigidity of various degrees during erection. Furthermore, the 3 types of cavernosus muscles’ insertion into the TA (fibrous, muscular belt or beltless) appear to produce variable degrees of CC compression. However, further studies are required to investigate the role of the different types of TA and cavernosus muscles’ insertion in the mechanism of erection.

REFERENCES

1. Andersson KE, Wagner G (1995): Physiology of penile erection. Physiol Rev 75:191–236.

2. Bitsch M, Kromann-Andersen B, et al. (1990): The elasticity and the tesile strength of tunica albuginea of the corpora cavernosa. J Urol 143:642–644.

3. Bosch RJ, Bernard F, et al. (1991): Penile detumescence: Characterization of three phases. J Urol 146:867–871.

4. Goldstein AMB, Meehan JP, et al. (1985): The fibrous skeleton of the corpora cavernosa and its probable function in the mechanism of erection. Br J Urol 57:574–577.

5. Hsu GL, Brock G, et al. (1994): Anatomy and strength of the tunica albuginea: Its revelance to penile prothesis extrusion. J Urol 151:1205–1208.

6. Lue TF (1998): Physiology of penile erection and pathophysiology of erectile dysfunction and priapism. In: Campbell’s Urology, 7th edition. Walsh PC, Retik AB, Vaughan ED, Wein AJ, (Eds). Philadelphia: WB Saunders Co, pp 1157–1180.

7. Shirai M, Ishii N, et al. (1978): Hemodynamic mechanism of erection in the human penis. Arch Androl 1:345–349.

8. Tamaki M (1992): Mechanism preventing backflow from the canine corpora cavernosa to arteries in the rigid phase of penile erection. Urol Int 48:64–70.

[Ayoz]

There's a lot of useful information in here. What do you make of it?

[Iguana]

Ayoz, I think this could be the key as to why some guys are such hard gainers while others gain almost effortlessly. The report says "In 20 cadaveric specimens, the TA (tunica albuginea) of the CC (corpus cavernosum) was formed of two layers: an inner circular and an outer longitudinal (Figure 1). In six of the 28 specimens, it consisted of three layers: an inner circular, intermediate longitudinal and outer circular (Figure 2). In the remaining two specimens, the TA was formed of a single longitudinal layer "

So out of 28 cadavers the breakdown was:

7% (2 men) - 1 Layer Tunica
71.5% (20 men) - 2 Layers Tunica
21.5% (6 men) - 3 Layers Tunica

You would think the single longitudinal layered men could gain some massive girth very easily. Well, not these guys, but other living guys could. If this is an accurate cross section of most men, it could explain the easy, medium and hard gainers. The percentages look pretty close to what we hear from newbies starting PE. Think about it, if one guy has a 1 layer tunica how much easier will it be for him to gain as opposed to a guy with 3 layers? I guess the good new is you have about a 78.5% chance of being an easy to medium gainer.

Here's when a generous doctor and with a shiny new MRI might come in handy!

[remek]

I remember this thread. I think hobby posted it.

If the tunica is in fact a major limiting factor in PE (which it probably is), then this can explain a lot - and it's also saddening to the 21.5 percent of men who have 3 layers of tunica.

Here's when a generous doctor and with a shiny new MRI might come in handy!

But if you add the ability to know, would you want to? What would it change - except bring light to the fact that you may have to PE for 10 years opposed to 1 or 2? Who wants to know that!

That said, I wonder if there are physiolgoical differences between the men who have 3 layers and the men who have 1.

[Iguana]

Yea, Boy, talk about shooting your motivation in the head if you found out you had 3 layers.
But, the data to the PE community as a whole might be valuable. Like you said, it would certainly explain a lot of things.

Originally Posted by remek

That said, I wonder if there are physiolgoical differences between the men who have 3 layers and the men who have 1.

Hey, it might be a good thing? They could have had massive girth!

[Handcramp]

While it's fascinating to learn that there can be such anatomical variation in penile structure, we cannot really say that it has any relationship to PE potential. Unfortunately, it required post mortem dissection to discover the tunica construction variation among individuals, at which point it's a bit late to be concerned with PE. What we need is a way to determine the tunica variant among living volunteers willing to enter into a strictly controlled PE trial, after which we'd learn whether or not gains are dependent upon tunica style. Until then it's nothing but speculation, which is fun, but still just speculation. Consider, too, that the original sample size was small. Would the percentages change significantly with a larger sample? Are there any correlations between race and tunica variant? Was there any relationship between adult natural penis size and tunica type? It would be great if the medical community took an interest in this aspect of male anatomical variation.

[Iguana]

Originally Posted by Handcramp

...we cannot really say that it has any relationship to PE potential.

Handcramp, I have to disagree. Granted there has been no scientific corelation between tunica layers and PE potential. But common sense woud have to dictate that there would have to be a definite relationship. The tunica defines penis size. It's what gives the organ structure and regidity. The phenomenon of Megalophallus shows that when the tunica's integrity is compromised the result is an enlargement of the organ. Having 3 layers of dense fibrous tissue to stretch or expand would definitely be more difficut than 1 or 2 layers. The laws of physics dictates it would be stronger and more difficult to injure. More tissue means more resistance. It doesn't mean guys with 3 layers could not gain. I just belive it would be much more difficult.

SOMETHING is responsible for guys who do everything right and still don't gain.

Originally Posted by Handcramp

...
Consider, too, that the original sample size was small. Would the percentages change significantly with a larger sample?

Maybe. But it doesn't negate the fact that this study shows there are most definitely percentages of men out there with a least 3 differing tunica types.

Originally Posted by Handcramp

...
Are there any correlations between race and tunica variant?

Would be interesting to know. Unfortunately, the report didn't say. But you would think if there was, it would have been mentioned.

Originally Posted by Handcramp

...
Was there any relationship between adult natural penis size and tunica type?

This also would be good to know. Again, you would think if there were a relationship it would have been mentioned.
But, maybe not. Who knows?

[Handcramp]

Originally Posted by Iguana

Handcramp, I have to disagree. Granted there has been no scientific corelation between tunica layers and PE potential. But common sense woud have to dictate that there would have to be a definite relationship. The tunica defines penis size. It's what gives the organ structure and regidity. The phenomenon of Megalophallus shows that when the tunica's integrity is compromised the result is an enlargement of the organ. Having 3 layers of dense fibrous tissue to stretch or expand would definitely be more difficut than 1 or 2 layers. The laws of physics dictates it would be stronger and more difficult to injure. More tissue means more resistance. It doesn't mean guys with 3 layers could not gain. I just belive it would be much more difficult.

SOMETHING is responsible for guys who do everything right and still don't gain.

Let's not confuse "common sense" ideas with what we actually know (or don't, more importantly) from evidence. I'd hope to keep PE discussions from sinking to the level of religion. All I am arguing for is adhering to a high level of intellectual honesty and discipline, and a willingness to preface speculation with an admission that it is nothing more than that. Read carefully through the paper and you will see a clear distinction between what the author knows (data or evidence, e.g. tunica construction variations), and what is offered as speculation (relationship to erectile firmness). Men read these forums and attempt to enlarge their penises--some of these attempts come to an awful end in the ER. It should always be clear what is known, and what is not.

Nobody even knows what exactly happens when a penis is successfully and permanently enlarged by the techniques we use.

Nobody knows why some men who fail to gain from hanging can gain from jelqing and stretching, or vice versa.

Some men claim to loose nothing after quitting cold-turkey, while others regress without cementing.

Nobody actually knows what proportion of men who seriously practice PE fail, what proportion gain modestly, and what proportion do very well. As an example, of the nearly 90,000 members of TP, only a small number post regularly. How many who fail never make their presence known in the forums? How many who gain something also remain silent, for whatever reason? We rely exclusively on self reporting for all things PE. Self reporting is notoriously unreliable. We have almost no control over the "data" presented within the PE community, hence making conclusions is risky business.

[remek]

Handcramp: You're touching up on an important point I talked about in another thread. I personally believe that there's probabably more men who don't post but still gain than vice versa.

The reason being: A lot of men who post are doing so because they aren't gaining. The gains are coming in as fast as they thought they would, so they start asking questions.

[Iguana]

Originally Posted by Handcramp

Let's not confuse "common sense" ideas with what we actually know (or don't, more importantly) from evidence. I'd hope to keep PE discussions from sinking to the level of religion. All I am arguing for is adhering to a high level of intellectual honesty and discipline, and a willingness to preface speculation with an admission that it is nothing more than that.

Handcramp, first off, my apologies if my viewpoint came off sounding dogmatic. I tend to do that sometimes when I feel strongly about something.

I don't think anyone here would argue your point. This is after all the PE Theory forum. Anything posted here is simply that -theory.
We are all here for one reason: to establish, practice, and promote effective penis enlargement techniques. Anything other than "intellectual honesty and discipline" will not help any of us reach this goal. I am not suggesting we start plugging holes in what we don't know with baseless speculation.

Unfortunately, we do not have the time, resources, or knowledge to conduct our own scientific analysis as to what works and what does not and what is and what is not. That being the case, we have no choice but to rely on the data we can obtain from pertinent studies and from "self-reporting" and to do our best to correctly interpret it. What is pertinent as far as how any studies relate to PE? Well, unfortunately no one is going to tell us, we have to decide that for ourselves. We have to use good "common sense" in making any assumptions, and as to the extent that we are able - test our assumptions.

As far as these studies and self-reporting goes, for now, sadly, these methods are all we have. Studies that might pertain to PE are few and far between. So instead of chucking anything we can't prove shouldn't we closely scrutinize them with an open mind? It's either that or trial and error and I think we've done enough of that.

Am I really going out on a limb in concluding that 3 layers of tissue might be harder to stretch than 1 or 2?