THE PROSTATE is the big chestnut shaped gland at the base of the bladder and is easily felt and probed by a finger or cock through the arsehole. In its course from the bladder to the pump-bulge (up behind the balls) of the penis, the urethra--the delivery tube for semen as well as urine through the penis--passes pretty much vertically through the central axis of the prostate, from its upper surface, through its very muscular gland tissue, to the apex of the prostate which sits atop the upper surface of the hidden rear-most part of the penis whose pump-bulge, surrounded by its powerful main ejaculatory muscle, finally propels the semen from the penis. Through the back of its middle part, the prostate is penetrated from behind by the terminally narrowed parts of two pencil-thick tubes, the ampullae of the vas deferens, which are, on the left and right side, formed by the vas deferens itself (which conducts only sperm from the balls) joining with the discharge outlet of the seminal vesicle of each side. The seminal vesicles are long (about 4-6 inches) thick folded tubular glands with very muscular walls, which secrete and at the man's orgasm pump by far the largest contribution (60% by volume) to the semen straight through the ampulla and into the part of the urethra coursing vertically through the prostate. The secretion of the seminal vesicles is thick and whitish-yellow, and contains fructose sugar to nourish the sperm, and very high concentrations of male prostaglandins----the hormones which cause the woman's vagina, womb and egg tubes to dilate and rhythmically--and very pleasurably--contract to encourage uptake of the ejaculated semen and transport of the sperm themselves to the egg way up inside the woman's pelvis. The function of the prostate is 1. To make a thin milky secretion which is ejaculated first (ahead of the sperm--second-in-line--and the final very much bigger fluid dump from the seminal vesicles), which is an alkaline secretion which neutralises the protective sperm-toxic acidity of the vagina and cervix. 2. To act as the final in-pelvis common chamber for receiving and then delivering, very powerfully spurt-wise, all three of the secretions making up the semen. The chamber is of course the section of the urethra which lies within the prostate itself and which dilates, from a volume of almost nothing in its collapsed, sexually non-active state, to a volume of some 2-5 cc several times over as it empties itself pump-wise during the man's orgasm. This very active urethral pumping within the prostate is produced by hard rhythmic contractions of the thick muscular outermost layer of the wall of the prostate. During the last 10-20 minutes of the man's buildup to orgasm, the prostate gland cavities secrete very copiously, and this, together with the greatly increased blood-flow through the gland, causes the prostate to expand to about twice its resting size. With the first few contractions of actual ejaculation, the prostate---pumping its first spurts of secretion before any other part of the man's seminal load---becomes transiently smaller. However, within one or two more contractions, the seminal vesicles and ampullae of the vas deferens--and in fact the whole 10" length of the vas deferens from the testicles to the ampullae deep within his pelvis---respond suddenly by pumping their very much larger contribution straight into the prostatic urethra; and at very high pressure. 3. To give Pleasure. The spurtings of, first, prostatic fluid, then second, the testicle fluid containing sperm and finally, the high volume secretion of the seminal vesicles, has a huge pleasure advantage to the man. This is because the nerve-rich front wall of the prostatic urethra---the deep pelvic common-pathway pumping chamber---is exquisitely sensitive to the impacting against it of the strong spurtings from the prostate gland ducts as well as from the ampulla of each side, right and left, whose terminal portion opens onto the back wall of the prostatic urethra and in the second and third phases of the man's ejaculation discharges its more copious and hard-spurted load of, first, testicle secretion and then seminal vesicle secretion directly against its intensely pressure-sensitive front wall. Whilst the earliest gland-arising pleasure sensations of male sexual "build up" and orgasm are produced by increasing secretion in the testicles and seminal vesicles and prostate, causing much increased fullness and tenseness in those glands urging the man to increasing thrusting and eventually to ejaculate, it is thought that the most intense pleasure of his orgasm---which he experiences only while he is actually ejaculating usually his strongest and most copious spurts--- is caused by the impact of the ampulla spurtings from his overloaded and super-tense seminal vesicles into the prostatic urethra. It is the delicious awareness of the sensation of those most forceful spurtings into his prostatic pumping chamber which finally cause the man to yell out his incredible, almost blinding pleasure at this stage of his orgasm. The sudden maximal filling and the resulting expansion to maximum openness of the prostatic urethra causes ---in the moment before ejaculation of the spurt so formed in it---masses of stretch-sensitive nerves in its walls to transmit the most intense of the pleasure feelings the man achieves during intercourse ---of deep pelvic overload and tension, which as we know so well, just happen to urge the man to his most powerful and deepest thrustings into the woman and to hold his final ones fully "home" while he ejaculates in her--- with maximum ecstasy and usually up against her womb mouth. The delicious sensitivity of the prostatic urethra to fluid spurt impacts and to volume stretching is nicely appreciable by some men when a urethral catheter or some other soft tubular instrument is carefully slid through the cock until its end lies in the prostatic urethra and is carefully moved about there. The same mechanism accounts somewhat for the moderately deep pelvic pleasure a man gets from simply having a pee---the stream of urine passing through the prostatic urethra increasing the pressure within it (compare with ampullary spurts) and also the volume of it (compare with the effect of its dilation during ejaculation).