Site-dependent and interindividual variations in Denonvilliers' fascia: a histological study using donated elderly male cadavers.

Site-dependent and interindividual histological differences in Denonvilliers' fascia (DF) are not well understood. This study aimed to examine site-dependent and interindividual differences in DF and to determine whether changes in the current approach to radical prostatectomy are warranted in light of these histological findings. Twenty-five donated male cadavers (age range, 72-95 years) were examined. These cadavers had been donated to Sapporo Medical University for research and education on human anatomy. Their use for research was approved by the university ethics committee. Horizontal sections (15 cadavers) or sagittal sections (10 cadavers) were prepared at intervals of 2-5 mm for hematoxylin and eosin staining. Elastic-Masson staining and immunohistochemical staining were also performed, using mouse monoclonal anti-human alpha-smooth muscle actin to stain connective tissues and mouse monoclonal anti-human S100 protein to stain nerves. We observed that DF consisted of disorderly, loose connective tissue and structures resembling "leaves", which were interlacing and adjacent to each other, actually representing elastic or smooth muscle fibers. Variations in DF were observed in the following: 1) configuration of multiple leaves, including clear, unclear, or fragmented behind the body and tips of the seminal vesicles, depending on the site; 2) connection with the lateral pelvic fascia at the posterolateral angle of the prostate posterior to the neurovascular bundles, being clear, unclear, or absent; 3) all or most leaves of DF fused with the prostatic capsule near the base of the seminal vesicles, and periprostatic nerves were embedded in the leaves at the fusion site; and 4) some DF leaves fused with the prostatic capsule anteriorly and/or the fascia propria of the rectum posteriorly. Site-dependent and interindividual variations in DF were observed in donated elderly male cadavers. All or most DF leaves are fused with the prostatic capsule near the base of the seminal vesicles and some DF leaves are fused with the fascia propria of the rectum posterior. Based on our results, surgeons should be aware of variations and search for them to create a suitable dissection plane to avoid iatrogenic positive margins and rectal injury.