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Tunica Differences

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Tunica Differences

Very interesting.

Arch Androl. 2006 Jan-Feb;52(1):1-8.

Histologic study of the tunica albuginea of the penis and mode of cavernosus muscles’ insertion in it.

Shafik A, El-Sharkawy A, Khamis A, Zaghloul S, Abdel Gawad M, Elwy D.

Department of Surgery and Experimental Research, Faculty of Medicine, Cairo University, Cairo, Egypt.

The tunica albuginea (TA) is the outer covering of the corpora cavernosa (CCs) and corpus spongiosum (CS) of the penile shaft. The different histoanatomical patterns of the TA, as well as the mode of attachment of the ischio-/bulbo-cavernosus muscles (ICM, BCM) to the TA, were studied, aiming at elucidating their role in the mechanism of erection. Twenty-eight cadaveric specimens (18 adults, 10 neonatal deaths) were studied morphologically and histologically after staining with hematoxylin and eosin and Verhoeff-van Gieson stains. The TA consisted in 20 specimens of 2 layers: inner circular and outer longitudinal, in 6 specimens of 3 layers: inner circular, longitudinal and outer circular, and in 2 of only one longitudinal layer. The CS TA was formed of one layer of longitudinal fibers. The mode of cavernosus muscles insertion into the TA revealed 3 patterns. The conjoint BCM and ICM formed a fibrous belt over the CCs in 18 specimens, a muscular belt in 6 and no belt in 4. The functional role of the variations in the TA morphological structure is not exactly known. We hypothesize that the 3-layered TA gives more penile rigidity than the double and single layers. Considering the type of cavernosus muscles insertion into the TA, it appears that the fibrous belt exerts more CC compression than the other 2 types of insertion.

Weird, I wonder if the neonatal specimens corresponded to the single layered TA, non belted CMs, or the other abnormal cases.


-Still bitter the y2k bug was a dud.

-My dear boy, do you ask a fish how it swims? (No.) Or a bird how it flies? (No.) Of course not. They do it because they were born to do it...

Yeah, I hope someone with access will get the full article.

It looks like that journal imposes a 12 month delay between print publication and online institutional access. Maybe someone else has special access priviledges though.


-Still bitter the y2k bug was a dud.

-My dear boy, do you ask a fish how it swims? (No.) Or a bird how it flies? (No.) Of course not. They do it because they were born to do it...

Soon we’ll have someone here asking how they can get a “third layer” for stonger erections. :rolleyes:

Originally Posted by hobby
Yeah, I hope someone with access will get the full article.
The PDF is >2 MB (too large to post here). So here is some text instead, without the high-res photo illustrations:

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.

Very interesting. It could be an important clue as to why some people have good PE gains while others have very little. I think I must have about 17 layers of tunica, because that bitch just won’t stretch!

The way I visualize it, the circular layer of tunica would be best at resisting radial expansion (girth), while the longitudinal layer would be best at resisting longitudinal expansion (length). The vertebral discs of the spine are constructed similarly (the anulus fibrosis of the disc).
Some guys apparently don’t even have this circular layer, which could be the guys who have an eaisier time with girth gains, etc.
Like west said, more layers may mean more rigidity, but I bet it means more difficulty to grow.


Horny Bastard

Thanks, Para.

I’m surprised there is so much variation. Surely these differences have some influence on PE results.

Maybe it is possible to change the tunica (for better PE results)

Here is an article in which is written that “glucose levels” have a major impack on the tunica thickness.
http://www.asiaandro.com/1008-682X/6/365.htm

I think newbies have a tunica which is way thinner than the tunicas of the PE vets here. I also think that’s why newbies gain so fast.


GOAL for December 2007: 8 X Red Bull

GOAL for December 2025: 14 X 10

Yes, from this it seems plausible that many of the big girth gainers are among the 7.2% blessed with a single-layer tunica, and many of the real hard-gainers may have the triple layer variety. Given the articles’ correlation of this with erection tumescence, it would be interesting to do a survey comparing the relative stiffness of erections between easy and hard gainers.

.Also, in regards to the above comment on glucose levels, there is only one possible correlation between glucose levels and tunica rigidity; that is that prolonged, ELEVATED glucose levels may lead to a MORE rigid tunica as a result of microvascular damage, sclerosis, and scar tissue formation. This is the same PATHOLOGICAL process that leads to renal failure, impotence, blindness, and extremity amputations in diabetics every day. To raise your glucose levels is to give yourself diabetic complications and a limp, stiff-tunica dick, and to lower them will lead to delirium, coma, and death. In short, bad idea.

Agreed, Diabetes is no way to change your dick, unless you just want to ruin it. The article actually describes thinning of the tunica, not thickening, and a resultant loss in the ability to hold venous blood in the penis. Thinning occurs from a breakdown in collagen synthesis, from some chemical byproducts of hyperglycemia.


Horny Bastard

I wonder how I can get a third layer for stronger erections?

Never mind.

j/k west. :D

Originally Posted by mravg
Agreed, Diabetes is no way to change your dick, unless you just want to ruin it. The article actually describes thinning of the tunica, not thickening, and a resultant loss in the ability to hold venous blood in the penis. Thinning occurs from a breakdown in collagen synthesis, from some chemical byproducts of hyperglycemia.

I see, I didn’t read that.. Still seems like a high price to pay, though. Maybe while we are at it, we could self-inflict spinal cord damage by jumping out of a window so that we might induce a priapism, and that might lead to megalophallus.dude, I’d be HUGE!! LOL!

Hmm, I am hypoglycemic. I wonder if that is why I have gained so well in the 3 months I’ve been PEing.


Start nov05 6.313" BPEL x 5.250" EG

Current 7.5" BPEL(goal reached!) x 5.375" EG

Goal 7.5" BPEL x 6.25" EG


Last edited by sumyunguy : 01-23-2006 at .
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