Quite a number of the fascinating changes and vital reactions which occur in the man’s prostate, seminal vesicles and inner pelvic muscles during his sexual arousal, and especially during his buildup to orgasm and during actual ejaculation, can easily be felt and pretty fully appreciated by inserting a finger deeply into his rectum while he is masturbating; but better still---and more dramatically---while he is partnering a woman in intercourse. During early sexual arousal of the man, through increase in bloodflow through it and by a sudden upping of its secretion activity, his prostate swells very considerably and increases in firmness somewhat; but remains only rubbery-firm compared to the greater hardening of it which occurs while he is building to orgasm, and the almost stone-hardness of it during his orgasm and finally ejaculation itself. It its swollen sexually excited state while the man is engaging in masturbation or intercourse, his prostate--with its chestnut shape and vertical midline shallow groove up the middle of its back surface---can be very easily located and felt by carefully and slowly a finger into his rectum and then gently sweeping the fingertip forwards onto the front wall of his rectum--which provides only the thinnest, softest, very mobile barrier to the exploring fingertip. Probing, stroking and massaging of the prostate by a finger inserted into the rectum is---once initial embarrassment and timidity and minor discomfort are overcome--- is an extremely pleasurable, usually intensely arousing and potentially extremely satisfying experience for most males. In anal intercourse between men, low angle penetration by the active partner of the passive partner with the latter on his back, easily and reliably ensures direct thrusting of the head of the entering penis against the back of the passive partner’s prostate. Orgasms for the passive partner resulting from such targeting of the prostate are usually especially intense, particularly if self-masturbation or masturbation of him by his active partner or another person is engaged in simultaneously with the anal intercourse. With the approach of the man’s orgasm, the prostate firms up further and enlarges even more dramatically than in the arousal and build-up stages of masturbation and intercourse. Finally, with the onset of orgasm, the prostate becomes almost stony hard and, exactly simultaneously with the sudden orgasmic first gasping or crying out and overall stiffening of the body of the man, the bulging prostate executes its first hard propulsing contraction---driving its pent-up milky secretion through several short connecting ducts straight into that part of the urethra which passes through the prostate itself. As explained above, these spurting of the prostatic fluid onto the front wall of the prostatic urethra are productive of some of the most intense feelings of physical orgasmic pleasure that the male can experience. The first major ejaculatory contraction of the prostate is always preceded by a transient, slight quivering---lasting some two to three seconds only---of its thick muscular outer covering. This extremely tense quivering of the outer, gland-embracing part of the prostate’s muscular system, although of very high frequency and twitchy in nature, is very easily detected by a fingertip gently pressed to the back of the prostate. Taken together with the simultaneous extreme hardening of the prostate overall, this tremulous, almost shivery muscular activity in the prostate’s sheathing muscle layer is the sure and constant signal of the oncoming ejaculation---which is by this stage now actually unstoppable by the man. Accompanying this preparatory tensing and twitching of the prostate’s muscle coating, the pulsing---also easily felt by the exploring fingertip---of the arteries within in and coursing upon the back surface of the prostate increases dramatically to a perceptible hard throbbing in time with the man’s heartbeat (distinguishing it from the widespread pelvic muscular contractions which accompany his orgasm). This additionally strong pulsing of these arteries continues throughout the male orgasm, but is less detectable during the distracting powerful muscular contractions of the man’s anal ring muscle around the examining finger, and because of other major muscular throbbings occurring deep within his pelvis against and around the exploring fingertip, all of which inevitably accompany the ejaculatory phase of his orgasm. However, following the major orgasmic contractions of the man’s prostate and muscles of his pelvis, penis and his body overall, the prostate softens considerably, enabling the very rapid immediately post-orgasmic pulsing of the arteries to be very easily felt in the back part of the prostate as well as with all of the surrounding pelvic tissues; some of the medium-sized pelvic arteries of the man become especially more pulsatile following him experiencing an especially prolonged or intense orgasm such as may follow intense additional stimulation by rectal fingering. The secretion of the prostate gland makes up only 20% of the total volume of the man’s ejaculate. But it is the first major component of the semen to be ejaculated by the man, and it is alkaline. It acts to temporarily neutralize the normal sperm-toxic bacteria-protective acid environment of the vagina immediately, or at least within a few penis thrusts of its being spurted and spread deeply in the vagina and against the woman’s waiting cervix. Following the first phase expulsive contractions of the prostate which result in the ejaculation of the prostatic secretion itself, about 0.5 cc of testicle secretion containing 300 million or so sperm is, after a 10 inch journey from each of the man’s testicles up into his groins, through the body-wall of his lower belly, and finally across the space of his pelvis----driven by muscular contractions of the man’s vas deferens during his arousal and buildup to orgasm---is at last pumped into the ampulla, from which it is spurted into the prostatic urethra and then contracted full-force upon by the entire muscular system of the prostate itself to immediately follow the man’s prostatic secretion through his penis and—hopefully---into the waiting body of the woman.