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Sources of Funding: RO1 DK10509701 (TL); R21 DK109912 (SPH,MLS); R01 DE022032 (SPH)

Introduction

Calcified Peyronie's plaque (CPP) is postulated to be of bone phenotype within a human penis. Rodents are used as models to investigate spatiotemporal mechanistic processes leading to CPP in humans; however, there are specific biomechanical differences between species. The comparable regions to program insults within rodents to induce the pathologically mineralized tissue similar to CPP are not well correlated. The objective of this study is to illustrate that the mouse corpus cavernosum glandus (CCG), instead of the mouse corpus cavernosum penis (CPP), is more analogous to the human corpus cavernosum (HCC).

Methods

Penile tissues from 12 Scx-GFP mice with ages 4 week, 5 week, 6 week, and 1.2 years, were dissected and processed following routine histology protocols. 6μm thick sections were stained with H&E, Massons' trichrome (TRI), Verhoeff's elastin (ELA), and DAPI. All sections were imaged using bright field or fluorescence microscopy techniques. Cell orientations along collagen fibers with age were analyzed using Image J Fiji.

Results

Figure: With age, CCG illustrated well-oriented struts at an angle of 32° to the baculum. Additionally, scleraxis and elastin expressions, and smooth muscle content increased within the struts, specifically in the 6 week-old mice. The expression of scleraxis indicated that the CCG contains mechanoactive collagenous and elastin-ridden struts that support biomechanical function of the baculum. Within the CCG of the mouse, there was more sinusoidal space in the younger age groups (4-6 weeks), and this space decreased with age, and elastin expression increased significantly (see 1 year). Compared to the CCG (A,C,E,G), the CCP (B,D,F,H) illustrated significantly lower expressions of scleraxis, elastin, and smooth muscle.

Conclusions

The collagen-producing fibroblasts within the CCG and CCP express scleraxis, indicative of local mechanoactive areas. Based upon orientation of cells expressing scleraxis, the biomechanical function of the CCP is to push the glans of the penis like a piston, while the CCG stiffens the penis during erection and pulls the glans of the penis back into the prepuce post-erection. The CCG is similar to the HCC with regard to compositional ratio of collagen to muscle, elastin localization, and biomechanical function and as such is a good model to study human penile physiology.

Funding

RO1 DK10509701 (TL); R21 DK109912 (SPH,MLS); R01 DE022032 (SPH)