Posts Tagged ‘seminal vesicles’

The Prostate Gland: Man’s Center of Gravity

February 16, 2019

Andrew Siegel MD  2/16/19

This entry can be considered to be “Prostate 101: Introductory Level.”  The prostate gland is a mysterious male reproductive organ that can be a source of curiosity, anxiety, fear and potential trouble. Since this gland is a midline organ nestled deep within the pelvis, I like to think of it as man’s “center of gravity.”  


Attribution: Jasper.o.chang [CC BY-SA 3.0 (; image unmodified; COG = center of gravity, COP = center of pressure

Where exactly is the prostate gland?

The prostate gland is located behind the pubic bone and is attached to the bladder above and the urethra below. The rectum is directly behind the prostate (which permits access for prostate exam).  The prostate is situated at the crossroads of the urinary and reproductive tracts and completely envelops the urethra, enabling its many ducts to drain into the urethra. However, this necessary anatomical relationship between the prostate and the urethra can potentially be the source of problems for the older male. With the aging process, this gland gradually enlarges and as it does so, this prostate enlargement can compress and obstruct the urethra, giving rise to bothersome urinary symptoms.  Note normal prostate on left and enlarged prostate on right in image below.

Benign_prostatic_hyperplasiaImage above, public domain, Wikipedia, illustrator unknown

What is the prostate, what purpose does it serve, and how does it function?

The prostate is a male reproductive gland that functions to produce prostate fluid, a nutrient and energy vehicle for sperm. The prostate consists of glandular and fibro-muscular tissue enclosed by a capsule of collagen, elastin and smooth muscle. The glandular tissue contains the secretory cells that produce the prostate fluid.

Semen is a “cocktail” composed of prostate fluid mixed with secretions from the seminal vesicles and sperm from the epididymides. The seminal vesicle fluid forms the bulk of the semen. The seminal vesicles and vas deferens (tubes that conduct sperm from testes to prostate) unite to form the ejaculatory ducts.

Prostate And Seminal Vesicles

At the time of sexual climax, prostate smooth muscle contractions squeeze the prostate fluid through prostate ducts at the same time as the seminal vesicles and vas deferens contractions squeeze seminal fluid and sperm through the ejaculatory ducts. These pooled secretions empty into the urethra (channel that runs from the bladder to the tip of the penis).  Rhythmic contractions of the superficial pelvic floor muscles result in the ejaculation of the semen.

What are the zones of the prostate gland?

The prostate gland is comprised of different anatomical zones. Most cancers originate in the “peripheral zone” at the back of the prostate, which can be accessed via digital rectal exam. The “transition zone” surrounds the urethra and is the site where benign enlargement of the prostate occurs. The “central zone” surrounds the ejaculatory ducts, which run from the seminal vesicles to the urethra.

Prostate Zones

Curious Facts About the Prostate

  • The prostate functions to produce a milky fluid that serves as a nutritional vehicle for sperm.
  • Prostate “massage” is sometimes done by urologists to “milk” the prostate to obtain a specimen for laboratory analysis.
  • The prostate undergoes an initial growth spurt at puberty and a second one starting at age 40 or so.
  • A young man’s prostate is about the size of a walnut, but under the influence of aging, genetics and testosterone, the prostate gland often enlarges and constricts the urethra, which can cause annoying urinary symptoms.
  • In the absence of testosterone, the prostate never develops.
  • The prostate consists of 70% glands and 30% muscle. Prostate muscle fibers contract at sexual climax to squeeze prostate fluid into the urethra.  Excessive prostate muscle tone, often stress-related, can give rise to the same urinary symptoms that are caused by age-related benign enlargement of the prostate.
  • Women have a female version of the prostate, known as the Skene’s glands.

Wishing you the best of health,

2014-04-23 20:16:29

A new blog is posted weekly. To receive a free subscription with delivery to your email inbox visit the following link and click on “email subscription”:

Dr. Andrew Siegel is a physician and urological surgeon who is board-certified in urology as well as in female pelvic medicine and reconstructive surgery.  He is an Assistant Clinical Professor of Surgery at the Rutgers-New Jersey Medical School and is a Castle Connolly Top Doctor New York Metro Area, Inside Jersey Top Doctor and Inside Jersey Top Doctor for Women’s Health. His mission is to “bridge the gap” between the public and the medical community. He is a urologist at New Jersey Urology, the largest urology practice in the United States.

The content of this entry is excerpted from his new book, PROSTATE CANCER 20/20: A Practical Guide to Understanding Management Options for Patients and Their Families

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Preview of Prostate Cancer 20/20

3-minute video trailer for Prostate Cancer 20/20

Andrew Siegel MD Amazon author page

Prostate Cancer 20/20 on Apple iBooks




Ejaculation: His and Hers

March 12, 2016

Andrew Siegel, MD   3/12/2016

One of the advantages of the specialty of urology is that it encompasses patients of both genders, unlike gynecology, which strictly involves females. Since I am board certified in Urology as well as in Female Pelvic Medicine, my practice allows me to have an equal balance of male and female patients. This gives me the opportunity to appreciate comparative male and female pelvic anatomy and function, which in reality are remarkably similar–a fact that may surprise you.

 A Few Brief Words on the Embryology of the Genitals.

Who Knew? Female and male external genitals are remarkably similar. In fact, in the first few weeks of existence as an embryo, the external genitals are identical.

The female external genitals are the “default” model, which will remain female in the absence of the male hormone testosterone. In this circumstance, the genital tubercle (a midline swelling) becomes the clitoris; the urogenital folds (two vertically-oriented folds of tissue below the genital tubercle) become the labia minora (inner lips); and the labio-scrotal swellings (two vertically-oriented bulges outside the urogenital folds) fuse to become the labia majora (outer lips).


(Comparison of genital anatomy,  1918 Gray’s Anatomy, Dr. Henry Gray, public domain)

In the presence of testosterone, the genital tubercle morphs into the penis; the urogenital folds fuse and become the urethra and part of the shaft of the penis; and the labio-scrotal swellings fuse to become the scrotal sac.  So, the clitoris and the penis are essentially the same structure, as are the outer labia and the scrotum.                                                                                              


Ejaculation is the expulsion of fluids at the time of sexual climax. The word “ejaculation” derives from ex, meaning out and jaculari, meaning to throw, shoot, hurl, cast. We are all familiar with male ejaculation, an event that is obvious and well understood and well studied. However, female ejaculation is a mysterious phenomenon and a curiosity to many and remains poorly understood and studied.

Male Ejaculation

Men often “dribble” before they “shoot.” The bulbo-urethral glands, a.k.a. Cowper’s glands, are paired, pea-sized structures whose ducts drain into the urethra (urinary channel). During sexual arousal, these glands produce a sticky, clear fluid that provides lubrication to the urethra. (These glands are the male versions of Bartholin’s glands in the female, discussed below).

Once a threshold of sexual stimulation is surpassed, men reach the “point of no return,” in which ejaculation becomes inevitable. Secretions from the prostate gland, seminal vesicles, epididymis, and vas deferens are deposited into the urethra within the prostate gland. Shortly thereafter, the bladder neck pinches closed while the prostate and seminal vesicles contract and the pelvic floor muscles (the bulbocavernosus and ischiocavernosus) spasm rhythmically, sending wave-like contractions rippling down the urethra to forcibly propel the semen out in a pulsatile and explosive eruption. Ejaculation is the physical act of expulsion of the semen, whereas orgasm is the intense emotional excitement and climax, the blissful emotions that accompany ejaculation.


(Male Internal Sexual Anatomy, permission CC BY-SA 3.0, created 18 April 2009)

What’s in the Ejaculate?

Less than 5% of the volume is sperm and the other 95+% is a cocktail of genital secretions that provides nourishment, support and chemical safekeeping for sperm. About 70% of the volume comes from the seminal vesicles, which secrete a thick, viscous fluid and 25% from the prostate gland, which produces a milky-white fluid. A negligible amount is from the bulbo-urethral glands, which release a clear viscous fluid that has a lubrication function. The average ejaculate volume is 2-5 milliliters (one teaspoon is the equivalent of 5 milliliters).

Who Knew?  While a huge ejaculatory load sounds desirable, in reality it is correlated with having fertility issues. The sperm can literally “drown” in the excess seminal fluid.

Female Ejaculation

This is a much less familiar subject than male ejaculation and a curiosity to many. Only a small percentage of women are capable of expelling fluid at the time of sexual climax.

The nature of this fluid is controversial, thought by some to be excessive vaginal lubrication and others to be glandular secretions. Although the volume of ejaculated fluid is typically small, there are certain women who ejaculate very large volumes of fluid at climax. Expulsion of fluid at climax may come from four possible sources: vaginal secretions; Bartholin’s glands; Skene’s glands; and the urinary bladder.


(Skene’s and Bartholin’s Glands, created 22 January 2007, original uploader Nicholasolan  en.wikipedia, Permission: CC-BY-SA-2.5, 2.0, 1.0; GFDL-WITH-DISCLAIMERS; CC-BY-S)

During female arousal and sexual stimulation, the vaginal walls lubricate with a “sweating-like” reaction as a result of the increased blood flow to the genitals and pelvic blood congestion, creating a slippery and glistening film. The amount of this lubrication is highly variable. Some women with female ejaculation can release some of this fluid at the time of climax by virtue of powerful contractions of the vaginal and pelvic floor muscles.

Bartholin’s glands are paired, pea-size glands that drain just below and to each side of the vaginal opening. They are the female versions of the male bulbo-urethral glands and during sexual arousal they secrete small drops of fluid, resulting in moistening of the opening of the vagina.

Skene’s glands (para-urethral glands) are paired glands that drain just above and to each side of the urethral opening. They are the female homologue of the male prostate gland and secrete fluid with arousal.

Scientific studies have shown that those women who are capable of ejaculating very large volumes are actually having urinary incontinence due to an involuntary contraction of the urinary bladder that accompanies orgasm. This is often referred to as “squirting.”

Bottom Line: In the animal kingdom (including human beings), sex is a clever “bait and switch” scheme. In the seeming pursuit of a feel-good activity, in reality—determined by nature’s evolutionary sleight of hand—participants are hoodwinked into reproducing. The ultimate goal of the reproductive process is the fusion of genetic material from two individuals to perpetuate the species.

The penis functions as a “pistol” to place DNA deeply into the female’s reproductive tract with ejaculation a necessity for the process. Similarly, the female genitals need to be sufficiently lubricated to optimize this process and the combination of vaginal lubrication from enhanced blood flow contributed to by Skene’s and Bartholin’s secretions will optimize nature’s ultimate goal.

Wishing you the best of health,

2014-04-23 20:16:29

A new blog is posted every week. To receive the blogs in the in box of your email go to the following link and click on “email subscription”:

Author of Male Pelvic Fitness: Optimizing Sexual and Urinary Health: available in e-book (Amazon Kindle, Apple iBooks, Barnes & Noble Nook, Kobo) and paperback: In the works is The Kegel Fix: Recharging Female Pelvic, Sexual and Urinary Health.

Co-creator of Private Gym and PelvicRx, comprehensive, interactive, FDA-registered follow-along male pelvic floor muscle training programs. Built upon the foundational work of Dr. Arnold Kegel, these programs empower men to increase pelvic floor muscle strength, tone, power, and endurance: or Amazon.  

Pelvic Rx can be obtained at, an online store that is home to quality urology products for men and women.  Use code UROLOGY10 at check out for 10% discount. 





“Un-Juiced”: When Ejaculation Goes South

March 27, 2015

Andrew Siegel MD   3/21/15

shutterstock_side view manjpeg

There is scarce medical literature on ejaculatory problems aside from those of ejaculatory timing issues (premature and delayed ejaculation) and hematospermia (blood in the semen). Despite being given short shrift in medical academia, not a day goes by in my clinical urology practice where I do not see at least several patients who complain of declining ejaculation function.

What Is The Origin Of The Word “Ejaculation”?

Ejaculation derives from ex, meaning “out”  and jaculari, meaning “to throw, shoot, hurl, cast.”

Trivia: You do not need an erection to ejaculate and achieve an orgasm. A limp penis cannot penetrate, but is eminently capable of ejaculation and orgasm.

If  “Semen” Or “Ejaculate” Is Too Medical For You:

The most popular slang is “cum.” It originates from the expression “come to climax” shortened to “come” and ultimately to “cum,” but not to be confused with the Latin “cum,” e.g., I graduated summa cum laude or the word meaning “along with being,” e.g., my basement-cum-gym! “Jizm,” “jism,” and “jizz” are also popular and are not to be confused with other         “–ism” words that mean a doctrine, e.g., socialism and capitalism! We cannot forget “splooge,” “spooge,” “spunk,” “wad,” “nut,” “load” and “man juice.”

What Happens To Ejaculation As We Age?

Ejaculation and orgasm often become less intense, with diminished force, trajectory and volume of semen. What was once an intense climax with a substantial volume of semen that could be forcefully ejaculated in an arc several feet in length gives way to a lackluster experience with a small volume of semen weakly dribbled out the penis.

Fact: I have never heard a patient complain that his penis is too large, nor have I ever heard anyone protest that his ejaculate volumes are too abundant.

Fact: The pervasive porn industry–where many male stars are hung like horses and whose penises seem capable of ejaculating flooding pools of semen– has given the average guy a bit of a complex.

So What’s The Big Deal?

Men don’t appreciate meager, lackadaisical-quality ejaculations and orgasms. Sex is important to many of us and getting a good quality rigid erection is foremost, but the culmination—ejaculation and orgasm—is equally vital. We may be 40 or 50 years old or older, but we still want to point and shoot like we did when we were 20. As the word origin indicates, we desire to be able to shoot out, hurl or cast like an Olympian Master Blaster and we yearn for that intensely pleasurable feeling of yesteryear.

Ejaculation Science 101

Sexual climax consists of three phases—emission, ejaculation, and orgasm. When the intensity and duration of sexual stimulation surpasses a threshold, emission occurs, in which secretions from the prostate gland, seminal vesicles, epididymis, and vas deferens are deposited into the urethra within the prostate gland. During ejaculation the pelvic floor muscles contract rhythmically, sending wave-like contractions rippling down the urethra to forcibly propel the semen in a pulsating and explosive eruption. Orgasm is the intense emotional excitement that accompanies the physical act of ejaculation.

Big Head Versus Little Head

Ejaculation is an event that takes place in the penis; orgasm occurs in the brain. The process of emission and ejaculation is actually a very complex and highly coordinated neurological event involving several specific centers in the brain (amygdala, thalamus and other areas), spinal cord and peripheral nervous system.

What’s Makes Up The Reproductive Juices?

Less than 5% of the volume of semen is actually sperm and the other 95+% is a cocktail of genital juices that provide nourishment, support and safekeeping for sperm. 70% of the volume comes from the seminal vesicles, which secrete a thick, viscous fluid and 25% from the prostate gland, which produces a milky-white fluid. A negligible amount is from the bulbo-urethral glands, which release a clear viscous fluid (pre-come) that has a lubrication function.

What’s Normal Volume?

The average ejaculate volume is 2-5 cc (one teaspoon is the equivalent of 5 cc). While a huge ejaculatory load sounds like a good thing, in reality it can cause infertility. The sperm can literally “drown” in the excessive seminal fluid.

Why Does The Seminal Tank Dry With Aging?

As we age, there are changes in the reproductive organs, particularly the prostate gland, one of the few organs in the body that enlarges as we get older. The aging prostate and seminal vesicles produce less fluid; additionally the ducts that drain the genital fluids can become blocked. In many ways, the changes in ejaculation parallel the changes in urination experienced by the aging male. Many medications that are used to treat prostate enlargement profoundly affect ejaculatory volume. Additionally, the pelvic floor muscles—which play a vital role in ejaculation—weaken with aging.

What About Those Pelvic Floor Muscles?

The pelvic floor muscles play a key role in ejaculation. The bulbocavernosus muscle (BC) is the motor of ejaculation, which supplies the “horsepower.” The BC surrounds the inner, deepest portion of the urinary channel. It is a compressor muscle that during sex engorges the spongy erection chamber that surrounds the urethra and also engorges the head of penis. At the time of climax, the BC expels semen by virtue of its strong rhythmic contractions, allowing ejaculation to occur and contributing to orgasm. A weakened BC muscle may result in semen dribbling with diminished force or trajectory, whereas a strong BC can generate powerful contractions that can forcibly ejaculate semen at the time of climax. 

How To Get The Juices Flowing Again?

Pelvic floor muscle training can be useful to improve the dynamics of ejaculation. The stronger the BC, the better the capacity for engorgement of the erection chamber that envelopes the urethra and the higher the ejaculatory horsepower, resulting in optimized urethral pressurization and ejaculation. The intensified ejaculation resulting from a robust BC can enhance the orgasm that accompanies the physical act of ejaculation.

Wishing you the best of health,

2014-04-23 20:16:29

A new blog is posted every week. To receive the blogs in your email in box go to the following link and click on “email subscription”:

Author of Male Pelvic Fitness: Optimizing Sexual and Urinary Health: available in e-book (Amazon Kindle, Apple iBooks, Barnes & Noble Nook, Kobo) and paperback:

Co-creator of Private Gym pelvic floor muscle training program for men: Gym—also available on Amazon

The Private Gym is a comprehensive, interactive, follow-along exercise program that provides the resources to strengthen the pelvic floor muscles that are vital to sexual and urinary health. The program builds upon the foundational work of Dr. Arnold Kegel, who popularized exercises for women to increase pelvic muscle strength and tone. This FDA registered program is effective, safe and easy-to-use. The “Basic Training” program strengthens the pelvic floor muscles with a series of progressive “Kegel” exercises and the “Complete Program” provides maximal opportunity for gains through its patented resistance equipment.

What The Heck is Urology?

August 24, 2013

Andrew Siegel, MD  Blog #116

“Urology” (uro—urinary tract and logos—study of) is a medical specialty concerned with the study, diagnosis, and treatment of diseases of the urinary tract in females and of the genitourinary tract in males. The organs under the “domain” of urology include the adrenal glands, kidneys, the ureters (tubes connecting the kidneys to the urinary bladder), the urinary bladder and the urethra (the channel that conducts urine from the bladder to the outside).  The male reproductive organs include the testes (i.e., testicles), epididymis (structures above and behind the testicle where sperm mature and are stored), vas deferens (sperm duct), seminal vesicles (the structure that produces the bulk of semen), prostate gland and, of course, the scrotum and penis.  The reproductive and urinary tracts are closely connected, and disorders of one oftentimes affect the other…thus urologists are referred to as  “genitourinary” specialists. Urology involves both medical and surgical strategies to approach a variety of conditions.

Urology has always been on the cutting edge of surgical advancements (no pun intended) and urologists employ minimally invasive technologies including fiber-optic scopes to be able to view the entire inside aspect of the urinary tract, as well as ultrasound, lasers, laparoscopy and robotics.  There is a great deal of overlap in what urologists do with other medical and surgical disciplines, including nephrology (doctors who specialize in medical diseases of the kidney); oncology (cancer specialists); radiation oncologists (radiation cancer specialists); radiology (imaging); gynecology (female specialists); and endocrinology (hormone specialists).

Urologists are the male counterparts to gynecologists and the go-to physicians when it comes to expertise in male pelvic health.  Urologists, in addition to being physicians, are also surgeons who care for serious and potentially life-threatening illnesses, particularly cancers of the genital and urinary tracts.  In terms of new cancer cases per year in American men, prostate cancer is number one accounting for almost 30% of cases; bladder cancer is number four accounting for 6% of cases; and cancer of the kidney and renal pelvis (the inner part of the kidney that collects the urine) are number six accounting for 5% of cases.  Urologists are also the specialists who treat testicular cancer.  Urologists also treat women with kidney and bladder cancer, although the prevalence of these cancers is much less so than in males. 

Very common reasons for a referral to a urologist are the following: blood in the urine, whether it is visible or picked up on a urinalysis done as part of an annual physical; an elevated PSA (Prostate Specific Antigen) or an accelerated increase of PSA over time; prostate enlargement; irregularities of the prostate on examination; urinary difficulties ranging the gamut from urinary incontinence to the inability to urinate (urinary retention).

Urologists manage a variety of non-cancer issues. Kidney stones, which can be extraordinarily painful, keep us very busy, especially in the hot summer months when dehydration (a major risk factor) is more prevalent. Infections are a large part of our practice and can involve the bladder, kidneys, prostate, or the testicles and epididymis.  Urinary infections is one problem that is much more prevalent in women than in men.  Sexual dysfunction is a very prevalent condition that occupies much of the time of the urologist—under this category are problems of erectile dysfunction, problems of ejaculation, and testosterone issues. Urologists treat not only male infertility, but create male infertility when it is desired by performing voluntary male sterilization (vasectomy).   Urologists are responsible for caring for scrotal issues including testicular pain and swelling.   Many referrals are made to urologists for blood in the semen.

Training to become a urologist involves attending 4 years of medical school after college and 1–2 years of general surgery training followed by 4 years of urology residency. Thereafter, many urologists like myself pursue additional sub-specialty training in the form of a fellowship that can last anywhere from 1–3 years.  Urology board certification can be achieved if one graduates from an accredited residency and passes a written exam and an oral exam and has an appropriate log of cases that are reviewed by the board committee.  One must thereafter maintain board certification by participating in continuing medical education and passing a recertification exam every ten years.  Becoming board certified is the equivalent of a lawyer passing the bar exam.

In addition to obtaining board certification in general urology, there are 2 sub-specialties within the scope of urology in which sub-specialty board certification can be obtained—pediatric urology, which is the practice of urology limited to children and female pelvic medicine and reconstructive surgery (FPMRS), which involves female urinary incontinence, pelvic organ prolapse, and other female uro-gynecological issues.  The FPMRS boards were offered for the very first time in June 2013, and I am pleased to announce that I am now board certified in both general urology and FPMRS.  There are approximately 100 or so urologists in the entire country who are board certified in the urology subspecialty of FPMRS.

In terms of the demographics of urology, although urology is largely a male specialty, women have been entering the urological workforce with increasing frequency.  This is because female students now comprise approximately 50% of United States medical school population. There are 10,000 practicing urologists in the USA, of which about 500 are women. Urologists have a median age of 53, so we are not a particularly young specialty. The aging population will demand more urological health services and the Affordable Care Act will result in the dramatic expansion of the number of American citizens with health insurance. These factors combined with the aging of the urological workforce and the contraction due to retirement, all in the face of growing demands, does not augur well for a balance of supply and demand in the forthcoming years.  Hopefully there will be enough of us to provide urological care to those in the population that need it.

Andrew Siegel, M.D.

Author of Promiscuous Eating: Understanding and Ending Our Self-Destructive Relationship with Food:

Available on Amazon in Kindle edition

Author of: Male Pelvic Fitness: Optimizing Sexual and Urinary Health, in press and available in e-book and paperback formats in the Autumn 2013.

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