The vascular endothelium plays an important role in proper blood flow, reproductive function, and resilience.
Waxy secretions called sebum lubricate and protect the glans of the penis but aggregate when left unrinsed and combine with shedding skin to form unwanted and malodorous smegma. Similar secretions are found in the ears, nostrils, rectum and mouth. These essential secretions are produced by the highly specialized epithelial cells, or glands, and are protected in the penile tissue by the foreskin sheath [1]. Unfortunately, a common and dangerous misperception stubbornly connects circumcision to increased survival by reducing secretions and cleaning requirements to prevent infection. This may have been a prevalent mindset under extreme heat where scarcity of soap and water was common. These secretions and supporting anatomy excised in a circumcision are in fact essential to proper penile function, including the body’s most sensitive mechanotransduction, or force exchange of external biochemical and biophysical signals, to internal responses. This apparatus is responsible for reproductive capacity after puberty and naturally leads to speculation about the direct implications of circumcision in early development and how it is related to trust and social cohesion. Evidence supports a disruptive social role in mother/infant bonding after circumcision when compared to intact infants [2].
To expound on the importance of the specialized structures found in the foreskin sheath, it is essential to also discuss how penile blood flow promotes reproductive function and resilience. The penile tissue is unique in that it can rapidly transform from lower to higher blood pressure/volume under positive feedback amplification. This includes the foreskin, a sheath of highly vascularized and innervated connective and epithelial tissue surrounding the muscular shaft. Like the surface area and intactness of a sail, this sheath commands the sensitivity and magnitude of mechanotransduction of the penis (“boat”), and its capacity and capability to function (voyage at sea). The sheath cover, especially the foreskin, maintains moisture to keep the superficial cells alive initiating command of the muscular penile shaft. Without this sheath, a process called keratinization, or elimination of living surface skin cells that function to maintain the penis, occurs. Keratinization significantly prohibits responsiveness by making the tissue more inert and nonresponsive, like putting holes in a sail before sailing. The foreskin sheath also improves healing and leukocyte recruitment after injury or infection.
Important in this process of healing is the highly specialized epithelium, or the vascular endothelium, part of the penile artery which is responsible for electrical and hydraulic conductivity, providing for more efficient energy transfer [3]. In effect its presence augments its functions like charging a battery faster with superior hardware connection. This efficient transfer results in more natural and efficient energy production from blood, and promotes this organ’s highly responsive and rapid biophysical transformation and stiffening. This process involves the glycocalyx, located on the endothelium surface in contact with the blood. It is a fine mesh net that stores biomolecules and receptors enhancing bioavailability for mechanotransduction and is shed in response to trauma [4]. The glycocalyx serves as a cupboard and stable environment for many different components, like biomolecules and receptors, and ‘breaks’ to aid in injury or inflammatory responses [4].
In the case of this injury response, it is akin to breaking the emergency glass covering a fire extinguisher, initiating the inflammatory response and leukocyte transmigration into the vessel wall for repair [4].
As mentioned earlier, the endothelium and its glycocalyx store biomolecules and receptors, most essential being nitric oxide (NO), along with aquaporin-1 water channel proteins acting as carrier to deliver highly volatile NO to smooth muscle before it quickly disintegrates. The delivery functions to sustain smooth muscle contractility and stiffness [3,5]. Disruption of this NO delivery leads to erectile dysfunction. This is commonly mitigated with inhibitory drugs that stabilize NO in the penile tissue attempting to delay penile muscle fatigue.
When the foreskin, endothelium and the membrane luminal glycocalyx are maintained, the arterial penile system including its associated nerves and muscles maintain the organ system’s sensitivity, function, and capacity to repair. Amputation of the foreskin, which includes these structures, compromise this function leading to physiological and psychological breakdown by crippling energy production, storage and delivery to blunt penile sensitivity and erection resilience/durability. This eliminates the immense capacity of the endothelial glycocalyx and aquaporin-1 in both selectively and rapidly delivering NO to smooth muscle [3,5].
Sources
[1] Anatomy and Physiology: The Unity of Form and Function, (12th edition), by Saladin, Kenneth S., McGraw-Hill Publishers, 2021.
[2] Marshall RE, Porter FL, Rogers AG, Moore J, Anderson B, Boxerman SB. Circumcision: II. Effects upon mother-infant interaction. Early Hum Dev. 1982 Dec;7(4):367-74. doi: 10.1016/0378-3782(82)90038-x. PMID: 7169032.
[3] Toussaint J, Raval CB, Nguyen T, Fadaifard H, Joshi S, Wolberg G, Quarfordt S, Jan KM, Rumschitzki DS. Chronic hypertension increases aortic endothelial hydraulic conductivity by upregulating endothelial aquaporin-1 expression. Am J Physiol Heart Circ Physiol. 2017 Nov 1;313(5):H1063-H1073. doi: 10.1152/ajpheart.00651.2016. Epub 2017 Jul 21. PMID: 28733452; PMCID: PMC5792199.
[4] Herrera, Marcela, and Jeffrey L. Garvin. "Novel role of AQP-1 in NO-dependent vasorelaxation." American Journal of Physiology-Renal Physiology 292.5 (2007): F1443-F1451.
[5] Weinbaum, Sheldon, et al. "The glycocalyx and its role in vascular physiology and vascular related diseases." Cardiovascular Engineering and Technology (2020): 1-35.
