<P> The seminal plasma provides a nutritive and protective medium for the spermatozoa during their journey through the female reproductive tract . The normal environment of the vagina is a hostile one for sperm cells, as it is very acidic (from the native microflora producing lactic acid), viscous, and patrolled by immune cells . The components in the seminal plasma attempt to compensate for this hostile environment . Basic amines such as putrescine, spermine, spermidine and cadaverine are responsible for the smell and flavor of semen . These alkaline bases counteract and buffer the acidic environment of the vaginal canal, and protect DNA inside the sperm from acidic denaturation . </P> <P> The components and contributions of semen are as follows: </P> <Table> <Tr> <Td> Gland (s) </Td> <Td> Approximate fraction </Td> <Td> Description </Td> </Tr> <Tr> <Td> testes </Td> <Td> 2--5% </Td> <Td> Approximately 200 - to 500 - million spermatozoa (also called sperm or spermatozoans), produced in the testes, are released per ejaculation . If a man has undergone a vasectomy, he will have no sperm in the ejaculation . </Td> </Tr> <Tr> <Td> seminal vesicles </Td> <Td> 65--75% </Td> <Td> amino acids, citrate, enzymes, flavins, fructose (2--5 mg per mL semen, the main energy source of sperm cells, which rely entirely on sugars from the seminal plasma for energy), phosphorylcholine, prostaglandins (involved in suppressing an immune response by the female against the foreign semen), proteins, vitamin C </Td> </Tr> <Tr> <Td> prostate </Td> <Td> 25--30% </Td> <Td> acid phosphatase, citric acid, fibrinolysin, prostate specific antigen, proteolytic enzymes, zinc (the zinc level is about 135 ± 40 micrograms / ml for healthy men . Zinc serves to help to stabilize the DNA - containing chromatin in the sperm cells . A zinc deficiency may result in lowered fertility because of increased sperm fragility . Zinc deficiency can also adversely affect spermatogenesis .) </Td> </Tr> <Tr> <Td> bulbourethral glands </Td> <Td> <1% </Td> <Td> galactose, mucus (serve to increase the mobility of sperm cells in the vagina and cervix by creating a less viscous channel for the sperm cells to swim through, and preventing their diffusion out of the semen . Contributes to the cohesive jelly - like texture of semen .), pre-ejaculate, sialic acid </Td> </Tr> </Table> <Tr> <Td> Gland (s) </Td> <Td> Approximate fraction </Td> <Td> Description </Td> </Tr>

Why does seminal fluid have a high content of​ sugar