The prostate develops from the distal urogenital sinus (the ventral portion of the cloaca) under the influence of testosterone from the fetal gonads. Epithelial outgrowths from the prostatic urethra bud into the surrounding mesenchyme from week 10 of embryologic growth. These buds subsequently signal back to overlying epithelial cells, inducing prostatic ductal formation. By week 12, there are five groups of tubules that progress to form the lobar anatomy of the prostate (1,2,3).

The normal prostate is a fibromuscular and glandular organ located within the male pelvis. It resembles an inverted pyramid, is approximately 20 to 30 mL in volume, and is 4 cm in length by 4 cm at it widest point. Commonly, the prostate is described as having an apex, the inferior limit, and a base on which the bladder rests. Throughout its length run the urethra and ejaculatory ducts. Related structures include the rectum and Denonvilliers fascia that lie posterior to the prostate and the paired seminal vesicles and ampullae of the vasa deferentia that lie posterolateral to the prostate and posterior to the bladder (Fig. 29.1).

Historically, intraprostatic anatomy has been difficult to define. Previously, the prostate has been described as a lobar structure, most commonly with five lobes: two lateral, a median, a posterior, and an anterior lobe. The zonal intraprostatic anatomical structure proposed by McNeal (4), following microscopic examination of the prostate, is now widely accepted. The zones include the peripheral zone, transition zone, central zone, and periurethral zone and the anterior fibromuscular stroma (5). The peripheral zone is most posterior and is composed of long, branched glands from which the majority of carcinomas are thought to derive. The central zone consists of short glands from which prostatic hypertrophy is thought to arise (Fig. 29.2).

The prostate is often described as having a “capsule”; however, it is not an anatomically discrete structure rather an aglandular fibromuscular layer contiguous and inseparable with the acini and parenchyma of the prostate. Surrounding this are the periprostatic fasciae, as described in the following section.

The urethra traverses the prostate from bladder to prostatic apex (approximately 1 cm from the pelvic floor). The external sphincter may be visualized, on cystoscopy, as a ridge of urethral mucosa distal to the verumontanum. The verumontanum represents the terminal end of the ejaculatory ducts as they course through the prostate from seminal vesicles/vas deferens, and at this point, the urethra angles upward by approximately 45 degrees. The opening in the apex of the verumontanum is known as the prostatic utricle (a remnant of the müllerian duct) (6).

With recent advances in robotic pelvic surgery, we have gained a more comprehensive understanding of the pelvic fascia. Unfortunately, the nomenclature of pelvic fascia is not well standardized; to simplify things, the pelvic fascia may be divided into the parietal endopelvic fascia that primarily covers pelvic musculature and the visceral endopelvic fascia covering the pelvic organs.

The parietal endopelvic fascia covers the muscles of the pelvic wall and floor (piriformis, obturator internus, levator ani, and coccygeus) and joins the transversalis fascia and the periosteum of the hipbones. By fusing with the underlying visceral fascia, it forms a thickened structure; the arcus tendineus fascia pelvis (tendinous arch) stretching from the puboprostatic ligaments (PPLs) to the ischial spine (7,8). Ventrally, the proximal prostate is covered by muscle fibers originating from the bladder, forming a structure known as the “detrusor apron.” The prostate is stabilized and supported by the PPLs that form fibrous bands from the visceral endopelvic fascia to the posterior aspect of the pubic bone and anterior to the urethral
sphincter. It is suggested that the PPLs play an important role in the suspensory system of the continence mechanism (9).

The visceral pelvic fascia invests the pelvic organs and neurovascular structures. It is attached anteriorly to the posterior surface of the pubis (forming the potential space—“the cave of Retzius”) and posteriorly to the ischial spine (7).