SEMINAL FLUID OR SEMEN

Generality

Seminal fluid, also known as sperm, consists of sperms immersed in a liquid medium called seminal plasma. The latter is essential for the maturation, metabolism and life of spermatozoa, as well as for their survival after ejaculation (emission, at the height of the sexual act (orgasm), of seminal fluid through the urethra). The spermatozoa, on the other hand, represent the male reproductive cells, which once released into the vagina, together with the other components of the sperm, go up the female reproductive system to fertilize the egg cell.

As soon as it is released, the seminal fluid coagulates, taking on a gelatinous consistency and a milky-white color. A few minutes after ejaculation, the process of dissolution of the clot and re-fluidification of the sperm begins, which is completed in the following 20 minutes by specific enzymes.

The synthesis of spermatozoa occurs inside the seminiferous tubules of the testes (contribution of 2-5% to the total volume of the sperm), while the plasma is produced by the seminal vesicles (contribution of 60-70% to the sperm volume), from the prostate ( 20/30%) and to a lesser extent by the bulb-urethral glands (<1%).

Components of seminal plasma

The composition of the seminal plasma is made up of various substances produced at the level of the epididymis, seminal vesicles and accessory glands, such as the prostate, located along the excretory path. proper function, including proteins, lipids, prostaglandins, hormones, ions, citric acid, fructose, vitamin C, a large variety of enzymes, zinc, carnitine and many other substances.

Each of these components is assigned a specific function:

fructose and carnitine (respectively useful as a source and production of energy), for example, are important in the metabolism and motility of spermatozoa;

several proteolytic enzymes are responsible for the already described liquefaction of the seminal clot;

similarly, citric acid also intervenes in the coagulation-liquefaction process of sperm;

lipids stabilize the membranes of spermatozoa, protecting them from thermal and environmental insults, and can represent an additional source of energy;

zinc probably has a direct and indirect bactericidal function, and stabilizes the chromatin of spermatozoa;

the bicarbonates of the seminal fluid have a buffer capacity, useful for neutralizing the acidity of the vaginal environment;

the mucus increases the mobility of the spermatozoa in the female reproductive system, creating channels inside the sperm, along which the same spermatozoa can advance without dispersing;

prostaglandins are instead involved in the suppression of the female immune response against the partner's spermatozoa (a common cause of infertility).

It is important to underline how some of these substances are synthesized or filtered in a specific district and as such they can be used as functional diagnostic markers of a specific anatomical structure. Fructose, for example, represents a very faithful index of the state of functionality of the vesicles. seminiferous, while citric acid is a typical marker of prostatic function. A good index of epididymal function is instead represented by the concentration of carnitine in the seminal fluid.

Characteristics of the sperm

Average ejaculate volume: 3/5 ml (greatly influenced also by the psychological conditions and the state of arousal of the subject).

Number of spermatozoa in ejaculated semen: 300 to 500 million.

Slightly alkaline pH: 7.2 / 8.

Seminal fluid osmolarity: iso-osmotic.

Color: white, opalescent.

Taste: also variable in relation to eating habits, with sweet, salty and bitter nuances. These and other physiological characteristics of the seminal fluid (with the exception of taste ...) are evaluated in an examination, called a spermiogram, which provides an indicative picture of male fertility.