<P> The function of the prostate is to secrete a slightly alkaline fluid, milky or white in appearance, that in humans usually constitutes roughly 30% of the volume of the semen along with spermatozoa and seminal vesicle fluid . Semen is made alkaline overall with the secretions from the other contributing glands, including, at least, the seminal vesicle fluid . The alkalinity of semen helps neutralize the acidity of the vaginal tract, prolonging the lifespan of sperm . The prostatic fluid is expelled in the first ejaculate fractions, together with most of the spermatozoa . In comparison with the few spermatozoa expelled together with mainly seminal vesicular fluid, those expelled in prostatic fluid have better motility, longer survival and better protection of the genetic material . </P> <P> The prostate also contains some smooth muscles that help expel semen during ejaculation . </P> <P> The classical description of a healthy human male prostate portrays it as slightly larger than a walnut . The mean weight of the normal prostate in adult males is about 11 grams, usually ranging between 7 and 16 grams . A study stated that prostate volume among patients with negative biopsy is related significantly with weight and height (body mass index), so it is necessary to control for weight . The prostate surrounds the urethra just below the urinary bladder and can be felt during a rectal exam . </P> <P> The secretory epithelium is mainly pseudostratified, comprising tall columnar cells and basal cells which are supported by a fibroelastic stroma - containing randomly oriented smooth - muscle bundles - that's continuous with the bladder . The epithelium is highly variable and areas of low cuboidal or squamous epithelium are also present, with transitional epithelium in the distal regions of the longer ducts . Within the prostate, the urethra coming from the bladder is called the prostatic urethra and merges with the two ejaculatory ducts . </P>

Where is the prostate gland located in a male