Vas Deferens

The vas deferens (or ductus deferens) is a 45-cm (18-in) long tube that ascends on the posterior border of each testis, penetrates the body wall through the inguinal canal, and enters the pelvic cavity.

From: Human Reproductive Biology (Fourth Edition) , 2014

Male Reproduction

Ryan Flannigan , Marc Goldstein , in Encyclopedia of Reproduction (Second Edition), 2018

Introduction

Development

The vas deferens (VD) is derived from the mesonephric or Wolffian ducts. Here, it is formed from the channel or linkage which forms between the mesonephros to the urogenital sinus. This occurs alongside the ureteric development. The VD then progressively lengthens as it descends along with the testis through the inguinal canal into the scrotum ( Gier and Marion, 1970; Hannema and Hughes, 2007).

Function

The VD's primary function is to transport sperm during emission form the epididymis to the ejaculatory duct. This is performed through a rhythmic propulsion of fluid and sperm at the time of emission. The VD also functions to store sperm in conjunction with the epididymis and convoluted VD. The VD produces fluid that facilitates sperm transport, and resorbs dead sperm and sperm parts that aren't ejaculated.

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Prostate

In Diagnostic Ultrasound: Abdomen and Pelvis, 2016

Seminal Vesicles and Vas Deferens

Vas deferens

Seminal vesicles

Bladder

Vas deferens

Seminal vesicles

Transverse transrectal ultrasound (TRUS) at the level of the seminal vesicles shows bilateral seminal vesicles and the vas deferens.

Vas deferens

Seminal vesicle

Bladder

Vas deferens

Seminal vesicle

More inferior transverse TRUS shows convergence of the vas deferens and seminal vesicles just above the base of the prostate.

Vas deferens

Seminal vesicles

Bladder

Vas deferens

Seminal vesicles

Transverse TRUS shows the vas deferens converging with the seminal vesicles. Their union will form the ejaculatory ducts, which enter the prostate base and course within the prostate enclosed within the central zone. The ejaculatory ducts empty into the urethra at the verumontanum.

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Prostate and Seminal Vesicles

In Imaging Anatomy: Chest, Abdomen, Pelvis (Second Edition), 2017

Seminal Vesicles, Vas Deferens

Vas deferens

Seminal vesicle

Vas deferens

Vas deferens

Seminal vesicle

Vas deferens

Two consecutive coronal T2 MR images show the vas deferens as they course medially over the posterior bladder to the seminal vesicles. The walls are thick and muscular and are low signal on T2 imaging.

Seminal vesicle

Urinary bladder

Vas deferens

Seminal vesicle

Rectum

Axial T2 MR shows the seminal vesicles between the urinary bladder and the rectum. The low-signal walls of the vas deferens should not be confused with tumor extension from prostate carcinoma.

Seminal vesicle

Seminal vesicle duct

Seminal vesicle

Prostate

Coronal T2 MR through the PZ of the prostate shows the "vesicular" appearance of the seminal vesicles with high signal intensity similar to fluid. The seminal vesicles secrete and store a fructose-rich, alkaline fluid, which is the major constituent of semen. They do not store sperm, which are transported from the testes via the vasa deferens during ejaculation. The duct of the seminal vesicle and the vas deferens join to form the ejaculatory duct.

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Infertility

Howard H. Kim , ... Marc Goldstein , in Principles of Gender-Specific Medicine (Second Edition), 2010

Mutations In The Cftr Gene

CBAVD, congenital unilateral absence of the vas deferens, congenital bilateral partial absence of the vas or epididymides, and congenital epididymal obstruction comprise the spectrum of vasal aplasia. CBAVD may occur in association with mesonephric (renal) anomalies or because of CF-related defects. Oates and Amos found up to 80% of men with CBAVD to carry mutations in at least one allele of the CFTR gene, 53 located on the long arm of chromosome 7. Chillon et al. reported a 72% mutation rate in at least one allele, 19% in both. 54 The gene encodes an ion channel protein but also participates in the formation of the distal two-thirds of the epididymis, vas deferens, seminal vesicle, and ejaculatory duct. As new mutations within the CFTR gene are discovered, the percentage of men with CBAVD who are found to harbor CFTR mutations increases. Perhaps all men with two orthotopic kidneys and CBAVD carry mutations in the CFTR gene; failure to detect these mutations reflects limitations of current testing methodologies. However, even if possible, testing for every mutation would not be practical, especially for rare mutations. Approximately 4% of whites are carriers of CFTR gene mutations. 55 Since men with vasal agenesis are likely carriers of CFTR mutations, the female partner must be tested for CFTR gene mutations to determine the risk of cystic fibrosis or CBAVD in the offspring prior to attempting ICSI. The penetrance of the CFTR carrier state in transmitting CBAVD appears to be low. 56 Men with CBAVD should be screened for renal anomalies with ultrasound or CT scan. As testicular sperm production in CBAVD is normal, epididymal sperm may be retrieved for ICSI.

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The Male Reproductive System

Richard E. Jones PhD , Kristin H. Lopez PhD , in Human Reproductive Biology (Fourth Edition), 2014

Vas Deferens

The vas deferens (or ductus deferens) is a 45-cm (18-in) long tube that ascends on the posterior border of each testis, penetrates the body wall through the inguinal canal, and enters the pelvic cavity. Once inside, each vas deferens loops over the urinary bladder and extends down toward the region of the urethra (Figures 4.1 and 4.8). The end of each vas deferens has an expanded portion, the ampulla, that serves as a reservoir for sperm. Each vas deferens enters an ejaculatory duct, which is 2   cm (1   in) long. These short ducts then lead into the urethra.

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Testes and Scrotum

In Imaging Anatomy: Chest, Abdomen, Pelvis (Second Edition), 2017

Vas Deferens, Spermatic Cord

Vas deferens

Head of epididymis

Tail of epididymis

Ureter

Seminal vesicle

Prostate

Corpus spongiosum

The tail of the epididymis is loosely attached to the lower pole of the testis by areolar tissue. The vas deferens (also referred to as ductus deferens) emerges from the tail at an acute angle and continues cephalad as part of the spermatic cord. After passing through the inguinal canal, the vas deferens courses posteriorly to unite with the duct of the seminal vesicle to form the ejaculatory duct. These narrow ducts have thick, muscular walls composed of smooth muscle, which reflexly contract during ejaculation and propel sperm forward.

External oblique muscle

Transversalis fascia (level of internal inguinal ring)

Internal oblique muscle

External oblique fascia

External spermatic fascia

Superficial (external) inguinal ring

Cremasteric muscle

The muscle layers of the pelvic wall have been separated to show the spermatic cord as it passes through the inguinal canal. The cremasteric muscle is derived from the internal oblique muscle, while the external spermatic fascia is formed by the fascia of the external oblique muscle.

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Testicular Anatomy and Physiology

J.B. Lin , D. Troyer , in Pathobiology of Human Disease, 2014

Vas (Ductus) Deferens

The vas deferens is a tubular structure measuring approximately 30–40  cm in length and arises from the caudal epididymis ( Figure 7 ). The distal portion of the ductus deferens dilates to form the ampulla. The ampulla joins the excretory duct to form the ejaculatory duct. The vas deferens is lined by a pseudostratified columnar epithelium composed of columnar cells and basal cells. The luminal surface of the columnar cell is lined by stereocilia. The epithelial layer contains folds, which become progressively complex toward the ampulla. Under the epithelium, the connective tissue stroma contains circumferentially oriented elastic fibers. Further out, the vas deferens is bordered by thick smooth muscle oriented in longitudinal fashion for the innermost and outermost layers. The middle layer runs circumferentially. During ejaculation, the muscle surrounding the vas deferens contracts, and transportation of sperm from epididymis to urethra occurs by peristaltic action.

Figure 7. Diagram of the ejaculatory tract.

 Reproduced with permission from A.D.A.M. ©1997–2012. http://health.rush.edu/healthinformation/in-depth%20reports/10/000639.aspx.

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Neurology of Sexual and Bladder Disorders

Pierre Clement , François Giuliano , in Handbook of Clinical Neurology, 2015

Ductus deferens

The ductus (or vas) deferens is a tubular structure with a narrow lumen (approximately 5   mm in diameter) surrounded by a thick muscular coat that is made up of circular and longitudinal muscle layers. Dual adrenergic and cholinergic innervations arising from the pelvic plexus have been reported (Alm, 1982). The sympathetic system contributes the highest density of fibers reaching the ductus deferens; the adrenergic innervation forms an extensive plexus throughout the muscle layers (Carvalho et al., 1986). Most of the cholinergic fibers are concentrated close to the epithelium (Yamauchi and Burnstock, 1969). NANC innervation, including VIP, NPY, and NO, is present in the ductus deferens (Owman and Stjernquist, 1988). Immediately before the emission phase of ejaculation, rapid and effective transport of spermatozoa occurs from the distal cauda of epididymis to the proximal ductus deferens due to sympathetic innervation stimulation. In addition, sympathetic tone controls peristaltic contractions throughout the ductus deferens that drive spermatozoa to the ampulla deferentia of the ductus deferens, which acts as a reservoir. The ampulla deferentia, located proximal to the prostate and adjacent to the seminal vesicles, fuses with the central ducts of the seminal vesicles to form the ejaculatory ducts.

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Emotional consequences of male infertility

Vassili Glazyrine , ... Ajay K. Nangia , in Psychological and Medical Perspectives on Fertility Care and Sexual Health, 2022

Cystic fibrosis transmembrane conductance regulator/congenital bilateral absence of the vas deferens

CBAVD occurs in 1%–2% of males with infertility [120]. This is an anatomic malformation that has two genetic causes: one that results from mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, and another that results from alterations in other genes involved in mesonephric ductal development, which are not yet known [121] . Patients with CBAVD are azoospermic, have a normal HPA axis, and as the name implies an absent or beaded/obstructed vas deferens on physical exam. Although a small subset of men with infertility have CBAVD, 95% of patients with cystic fibrosis (CF) will have CBAVD [122]. Fortunately, most men with CBAVD are asymptomatic or subsequently diagnosed with milder/atypical CF, involving mild pulmonary disease, gastrointestinal issues, and even pancreatitis [123]. Spermatogenesis is typically normal in these patients so ART can be used to help father biological children via ICSI following surgical sperm extraction [124]. Since the carrier frequency of the CF gene mutation is 1:20 in the general Northern European population, it is important to screen the female partner and provide genetic counseling to the couple prior to undergoing any fertility treatments [121].

From an emotional/psychological perspective, there are several aspects of the clinical picture that need to be recognized and discussed as part of counseling: shock of diagnosis and association with CBAVD; role of CF work up and for patient and female partner; risk of passing disease or carrier status to offspring; and role of preimplantation genetic diagnosis (PGD) of the embryo if the female partner is a carrier for the CFTR.

Unless the patient has known CF and is sent for fertility consultation, because of the known association with CBAVD and obstructive azoospermia, most patients are seen primarily for azoospermia and diagnosed with CBAVD by an outside provider, usually a urologist. It is often the male infertility specialist that makes the diagnosis of CBAVD, then has to explain the association with CF/CFTR mutations. On one level it is reassuring to know that the problem is a "blockage," but often a shock that it is associated with CF, which in the past was a life-threatening condition. Patients and partners can be more concerned that the man's disease will advance, and could possibly explain past symptoms. For example, one patient presented with a history of pancreatitis and was labeled a juvenile delinquent and alcoholic, when in fact his later presentation for azoospermia was a form of CF. Distressed and relieved at the same time, the patient cried and felt he had been validated after several years. The diagnosis of "genetic" can often lead to anxiety. Added to this, CBAVD has a 10% association with having a congenitally missing kidney, creating another level of anxiety at the initial consultation stage [125]. Again, genetic testing of both partners is needed to determine risk of passing the disease to offspring. Referral for genetic counseling, the need for ART with IVF-ICSI, PGD, and associated costs, as noted previously, are all part of an overwhelming situation for many men.

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Reproductive Medicine

Isaac Lam , Robert E. Brannigan , in Encyclopedia of Reproduction (Second Edition), 2018

Microductal Aplasia

Failure of the vas deferens to develop can occur unilaterally or bilaterally, each with a unique pathophysiological etiology. Congenital unilateral absence of the vas deferens (CUAVD) typically occurs due to abnormalities in mesonephric duct development. The mesonephric duct evolves into the epididymis, vas deferens, and ejaculatory duct, and thus CUAVD may present with defects in those anatomical parts as well. Because the mesonephric duct plays a role in renal development, CUAVD may suggest concurrent ipsilateral renal agenesis ( Weiske et al., 2000).

In contrast, congenital bilateral absence of vas deferens (CBAVD) is typically associated with mutations in cystic fibrosis transmembrane conductance regulator (CFTR) or other genes that regulate mesonephric duct maturation. Cystic fibrosis is an autosomal recessive disease. While patients with just one abnormal copy of the CFTR gene typically do not have cystic fibrosis, they often have CUAVD or CBAVD. At this point in time, over 1000 CFTR genes have been identified. The most common gene mutation in patients with cystic fibrosis, CUAVD, and CBAVD is delta-F508 which involves a deletion of phenylalanine at the position of 508 in the protein sequence. Because gamete production remains normal in most patients with CBAVD, reproduction can still be achieved through ICSI using surgically extracted sperm (Weiske et al., 2000).

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