Comparison of female and male prostate glands

Using gender as a descriptor can be odious. The concept of ‘lady’ doctor has landed securely in the 1980s trash can along with computer cards and photographic film. A doctor is a doctor. But is a prostate a prostate? As a Urologist one has a very clear view of what that organ involves. The prostate, as a discrete organ, sits anterior to the seminal vesicles, rectum and associated fasciae. From a normal adult walnut size, the prostate can sometimes develop to grapefruit size and always it is surrounded by an anatomical capsule. It has several zones with the transitional and peripheral zones causing immense pathology in adult and ageing men. There is general agreement about the fibromuscular stroma and the glands comprised of acini and ducts, which drain into the urethra proximal to the ejaculatory ducts. A multitude of embryological studies provide details on the development of the prostate from the urogenital sinus in humans and in animal models. The glands of the prostate express markers, the most notable being PSA because of its exceptional value in monitoring prostate cancer and other roles. The prostate has a significant role in male continence; surgery on the prostate resulting in excision or resection of the transition zone, placing continence at risk. Its primary reproductive role is to promote fertility by modifying seminal fluid. PSA is a kallikrein-related peptidase and in males its function is to cleave semenogelins in the seminal coagulum, thereby liquefying semen and promoting sperm motility. Female urethral glands appear to be important for sexual function. Jocelyn et al. [1] coined the term female ‘prostate’ for these glands and reported that sexual stimulation evoked the release of fluid from ducts that opened into the urethral lumen close to the meatus. Based on the work of Grafenberg, the popular term ‘G spot’ arose and the role of the urethra in the female sexual response was promoted [2]. Zaviacic [3] and Tomalty et al. [4] have written excellent reviews on the topic of the female ‘prostate’. Huffman was the first to use histology and three-dimensional wax reconstructions to characterise the urethral glands. He identified multiple ducts in the wall of the distal urethra that opened directly into the distal third of the urethral lumen. These were connected to a network of branching ducts in the urethral wall, which terminated in tubules and acini lined by a glandular epithelium. This work superseded the earlier clinical observations of Skene who provided a description of the gland ducts that in no way resembles descriptions provided by subsequent histological investigations. Zaviacic, who undertook extensive research of the urethral glands, felt Skene was undeserving of the eponymous name because the findings were erroneous, in particular the conclusion that there are two discrete glands in the wall of the urethra [4]. The description provided by Huffman has been supported by subsequent histological investigations [4]. It has also been demonstrated using immunohistochemistry that the glands surrounding the urethral lumen can express prostate marker proteins [3, 4]. Table 1 compares the features of the prostate in male prostate vs female ‘prostate’. When ‘prostatic markers’ have been studied in female urethral glands there have been variable findings with some glands expressing PSA and more expressing prostate-specific acid phosphatase (PSAP, [5]). We recently studied a series of complete urethras that were derived from a rapid autopsy programme [5]. Our findings demonstrated PSAP in the urethral glands of all seven urethras studied. Previous studies, which mostly used cadaveric tissue, failed to detect these prostatic makers in 20–50% of the urethras studied [5]. Therefore, while the sample size in our study was relatively small, the findings do suggest that tissue preservation in the previous studies may have affected the detection of the prostatic markers. Our findings indicate that PSAP is an important marker for female urethral glands. What PSAP (or indeed PSA) does in women is still to be determined by future research. A role for the glands in the female sexual response has been discussed, but the exact function of the secretion from the glands remains unclear. The key evidence for the glands playing a role in the sexual response comes from the demonstration of PSA and PSAP in urethral emissions evoked by sexual stimulation [4]. However, in women with large volume emissions, most of the fluid released is due to the leakage of urine. As originally suggested by Jocelyn et al. [1], female urethral glands likely contribute to normal lubrication of the vestibule. Terminology has been hampered by a lack of recognition of the glands as a feature of the urethra and not ‘periurethral’ or ‘paraurethral’ suggesting something in its vicinity. In large transverse slices that included the anterior vaginal wall, we demonstrated that the glands with long ducts were located primarily in the submucosal layer of the distal half of the urethra [5]. We did not find prostatic marker expression (nor for that matter glands) outside the urethra itself. This study also demonstrated PSAP expressing minor glands that empty directly into the urethral lumen. We proposed that these minor glands are responsible for urethral diverticula, whereas the major distal glands are responsible for cysts that occur in a perimeatal location (also known as Skene's duct cysts) [6]. Either of these major or minor glands may give rise to urethral adenocarcinoma and tissues should be studied for both PSAP and PSA when this occurs. However, a more detailed molecular profile of these glands is warranted to improve pathological assessments. Tomalty et al. [3] highlight the potential harm to the glands that may result from mid-urethral slings. A more proximally based loose sling (distal to the bladder neck) may prevent such harm. Female sexual function is important to female well-being, which in turn is arguably good for human health. Further stand-alone female research studies should be conducted to establish the precise role of female urethral glands in health. There is no conflict of interest from any authors.