The multilayered structure of the human corpus spongiosum.

Purpose. Urethral reconstruction is performed in patients with urethral strictures or for correction of congenital disorders. In the case of shortage of tissue, engineered tissue may enhance urethral reconstruction. As the corpus spongiosum (CS) is important in supporting the function of the urethra, tissue engineering of the urethra should be combined with reconstruction of a CS. For that purpose, detailed knowledge of the composition of the CS, more specifically its extracellular matrix (ECM) and vascularization is needed for scaffold design. The objective of this study is to analyze the microarchitecture of the CS through (immuno) histology and scanning electron microscopy (SEM). Methods. The CS including the urethra of patients undergoing male-to-female genital confirming surgery was harvested. This CS was fixed and processed for either (immuno) histology or for SEM. Results. Four layers could be distinguished in the CS; first a transition zone from urethra epithelium to a collagen rich layer, which was highly vascularized, followed by a second, elastin rich layer. The third layer was formed by veins, arteries and vascular spaces and the last layer showed the transition from this vascular rich region to the collagen rich tunica albuginea. In this layer collagen bundles intertwined with elastic fibres. In the CS different components of the ECM were visible and distinguishable. Conclusion. This study provides novel and detailed information on the microarchitecture of the CS and the distribution of vascularization, which is important for scaffold design in tissue engineering.