The Scoop on Semen – Facts
The Scoop on Semen - Facts
Semen is an organic fluid, also known as seminal fluid, that usually contains spermatozoa. It is secreted by the gonads (sexual glands) and other sexual organs of male or hermaphroditic animals and can fertilize female ova. In humans, seminal fluid contains several components besides spermatozoa: proteolytic and other enzymes as well as fructose are elements of seminal fluid which promote the survival of spermatozoa and provide a medium through which they can move or “swim.” The process that results in the discharge of semen is called ejaculation.
Internal and external fertilization
Depending on the species, spermatozoa can fertilize ova externally or internally. In external fertilization, the spermatozoa fertilize the ova directly, outside of the female’s sexual organs. Female fish, for example, spawn ova into their aquatic environment, where they are fertilized by the semen of the male fish.
During internal fertilization, however, fertilization occurs inside the female’s sexual organs. Internal fertilization takes place after insemination of a female by a male through copulation. In low vertebrates (amphibians, reptiles, birds and monotreme mammals), copulation is achieved through the physical mating of the cloaca of the male and female. In marsupial and placental mammals, copulation occurs through the vagina.
Composition of human semen
During the process of ejaculation, sperm passes through the ejaculatory ducts and mixes with fluids from the seminal vesicles, the prostate, and the bulbourethral glands to form the semen. The seminal vesicles produce a yellowish viscous fluid rich in fructose and other substances that makes up about 70% of human semen. The prostatic secretion, influenced by dihydrotestosterone, is a whitish (sometimes clear), thin fluid containing proteolytic enzymes, citric acid, acid phosphatase and lipids. The bulbourethral glands secrete a clear secretion into the lumen of the urethra to lubricate it.
Sertoli cells, which nurture and support developing spermatocytes, secrete a fluid into seminiferous tubules that helps transport sperm to the genital ducts. The ductuli efferentes possess cuboidal cells with microvilli and lysosomal granules that modify the semen by reabsorbing some fluid. Once the semen enters the ductus epididymis the principle cells, which contain pinocytotic vessels indicating fluid reabsorption, secrete glycerophosphocholine which most likely inhibits premature capacitation. The accessory genital ducts, the seminal vesicle, prostate glands, and the bulbourethral glands, produce most of the seminal fluid.
Seminal plasma of humans contains a complex range of organic and inorganic constituents.
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 the acidic environment of the vaginal canal, and protect DNA inside the sperm from acidic denaturation.
A 1992 World Health Organization report described normal human semen as having a volume of 2 ml or greater, pH of 7.2 to 8.0, sperm concentration of 20×106 spermatozoa/ml or more, sperm count of 40×106 spermatozoa per ejaculate or more, and motility of 50% or more with forward progression (categories a and b) of 25% or more with rapid progression (category a) within 60 minutes of ejaculation.
Via: Online Schools
-
Senators call for end to anonymous, prepaid cell phones [/caption] By Nate Anderson Earlier this month, the FBI revealed that the suspected Times Square bomber had used an anonymous... -
Hacker builds $1,500 cell-phone tapping device [/caption] LAS VEGAS – A computer security researcher has built a device for just $1,500 that can intercept some kinds... -
San Francisco board passes cell phone emission law [/caption] SAN FRANCISCO – In this city known for producing laws both path-breaking and contentious, legislators have forcefully stepped into... -
Nanotech Robots Developed to Fight Cancer [/caption] On Sunday, March 21, 2010, a group of United States researchers released their findings in the journal Nature. The... -
101 Ways to Lose Your Gut [/caption] Spend more of each day burning fat than you do storing it, and over time, you'll bury your belly...
-
Telco Harmonica 12 RJ11 (6x4) / 50 Pin Female, Wiring: USOC User Reviews Send this to a friend Telco Harmonica 12 RJ11 (6x4) / 50 Pin Female, Wiring: USOC Manufacturer: L-com,... -
The Reasoning Behind Cheap Car Insurance For Females Female drivers have fewer accidents than male drivers. That fact explains why insurance companies are willing to offer cheap car... -
Stem cells could help infertile women Researchers believe that they can produce new eggs in infertile women even if the ovaries are damaged or the woman... -
Maria Callas Memorabilia -> Opera Memorabilia Maria Callas may be the best known female opera singer of our time. While Pavarotti is... - Dog Breeding – Pros and Cons In every activity, there will always be pros and cons. This is also true with dog breeding. As the breeder,...
