Collagen and elastic fibers in the penis of human fetuses at 28 weeks postconception

Objectives: The extracellular matrix is a key element in penile function and pathology, yet little is known of its development. Herein we investigated the morphological organization of collagen and elastin in the corpora cavernosa and tunica albuginea of human fetuses. Material and Methods: The penises from 5 fresh human fetuses at 28 weeks postconception (WPC) were routinely fixed and embedded, and all staining procedures were carried out on paraffin sections. Collagen was evidenced by staining with: (1) Gomori's trichrome; (2) sirius red, followed by observation under polarized light, and (3) an antihuman collagen type-ill antibody. Elastin and the whole elastic system were revealed using an antihuman elastin antibody and Weigert's resorcin fucsin, respectively. Results: At this stage of fetal development, the albuginea is formed predominantly by dense bundles of collagen. Near the corpora cavernosa, the presence of type-ill collagen was also observed. Weigert staining showed numerous fibers of the elastic system in the albuginea. Type-ill collagen was found to be strongly positive in the cavernous trabeculae and in the connective sheath surrounding the central artery. Using Weigert staining and an immunolabeling method with primary antibody against human elastin, we found an important quantity of elastic system fibers in the trabeculae of the corpora cavernosa. Conclusion: In fetuses at 28 WPC the albuginea is formed predominantly by dense bundles of collagen. The trabecular structures of the corpora cavernosa present a significant quantity of type-ill collagen and elastic system fibers.