Sperm: composition, role and norms

Semen, or ejaculate, is a mixture of sperm and fluid produced by several glands of the male reproductive system. Sperm are produced in the testicles, then mature and are stored in the epididymis, and during ejaculation, they are joined by secretions from the seminal vesicles, prostate gland, and other structures. [1]

Sperm production occurs continuously after the onset of puberty and takes weeks. Popular wisdom often cites a period of approximately 74 days for formation, plus additional time for final maturation in the epididymis. Therefore, lifestyle changes or treatments for infertility rarely produce "instant" results. [2]

Ejaculate isn't just sperm in water. Most of it is seminal plasma: a nutritious and protective environment that helps sperm survive after exiting the man's body and navigate the first stages of their journey through the woman's reproductive tract. [3]

It's important to distinguish between "sperm" and "semen"—the entire mixture. These terms are often confused in everyday speech, leading to myths about the percentage of "sperm content" and incorrect conclusions based on the appearance of ejaculate. [4]

Table 1. Main sources of ejaculate components and their role

Structure	What is added to the ejaculate?	Why is this necessary?
Testicles and epididymis	Spermatozoa, maturation factors	Fertilization, maturation and "tuning" of spermatozoa
Seminal vesicles	A significant portion of the volume, including fructose and prostaglandins	Energy for movement, support for the environment
Prostate	Enzymes and molecules that affect the liquefaction and properties of ejaculate	Clot liquefaction, optimization of sperm movement
Bulbourethral glands	Mucous discharge during arousal	Lubricant, protection of the urethra

The proportions of glandular contributions vary, but in general the seminal vesicles and prostate gland provide the majority of seminal plasma. [5]

What semen consists of: spermatozoa and seminal plasma

Sperm carry genetic material and the "motor mechanism," but they are extremely vulnerable on their own. Without the right environment, they quickly lose their motility and ability to fertilize, especially when exposed to the acidic environment of the vagina or when exposed to moisture outside the body. [6]

Seminal plasma is a complex mixture of water, salts, sugars, proteins, lipids, enzymes, and signaling molecules. Its functions extend beyond "nutrition": it participates in coagulation and subsequent liquefaction of the ejaculate, influences the acidity of the environment, and contains antioxidant components and molecules that interact with the immune system of the female reproductive tract. [7]

Certain chemical markers in seminal plasma help determine which glands are functioning normally and which are not. Classic examples include fructose as a marker of seminal vesicle secretion, and citrate and zinc as markers of prostate secretion. This is used in clinical practice as part of an extensive evaluation for fertility issues. [8]

Modern reviews also highlight that seminal plasma contains many proteins and other molecules that have the potential to be biomarkers of reproductive disorders, but a “regular spermogram” alone does not always predict the chance of pregnancy, especially when using assisted reproductive technologies. [9]

Table 2. Key components of seminal plasma and their significance

Component or group	Examples	Practical meaning
Sahara	Fructose	Energy support for movement
Organic acids and salts	Citrate, bicarbonates	Impact on environmental properties and buffering
Microelements	Zinc and others	Participation in enzymatic reactions and properties of secretion
Enzymes and proteases	Liquefaction factors	Transition from a clot to a more liquid state
Immune and signaling molecules	Cytokines and others	Interaction with the mucous membrane of the female tract, immune effects

The summary of the composition and role of seminal plasma is based on modern reviews and clinical sources. [10]

What does sperm do after ejaculation: coagulation, liquefaction, transport

Immediately after ejaculation, semen typically appears as a thicker, partially gelatinous mass. This is a normal process: semen first coagulates and then gradually liquefies to allow the sperm to move more actively. [11]

Normally, liquefaction begins within a few minutes and is usually complete in approximately 15-30 minutes at room temperature. If liquefaction is not complete within 30 minutes, this is recorded in the report; if it is not complete within 60 minutes, this is also noted as an abnormality, as a significant delay can interfere with the assessment and may be associated with sperm functional problems. [12]

Viscosity and incomplete liquefaction are important for more than just the aesthetic appeal of the analysis. Overly viscous semen can hinder uniform mixing of the sample and accurate determination of concentration and motility, and in real-world physiology, it can impair sperm movement through cervical mucus. [13]

The acidity of ejaculate depends on the balance between the acidic secretion of the prostate gland and the more alkaline secretion of the seminal vesicles. Low acidity values may indicate insufficient seminal vesicle production or the presence of urine, so the indicator is routinely assessed over time, usually approximately 30 minutes after sample collection, and no later than 1 hour. [14]

Table 3. Dilution and viscosity: what is considered typical

Parameter	What usually happens	When might this be a problem?
The state immediately after ejaculation	Coagulated, thicker mass	It's normal in itself
Liquefaction	Usually completed in 15-30 minutes	If it is not completed within 60 minutes, it is recorded as a deviation.
Viscosity after liquefaction	Higher than water, but without any noticeable "stretchiness"	High viscosity may interfere with assessment and be associated with functional problems

Liquefaction time criteria and the approach to recording deviations are described in the World Health Organization guidelines. [15]

Normal values and variations: volume, concentration, mobility, acidity, appearance

One of the most common queries is "what is normal sperm?" It's more accurate to talk not about a single "norm," but about ranges and distributions, because indicators vary significantly within the same man and between different men, and a couple's fertility depends on both male and female factors. [16]

The World Health Organization's guidelines provide distributions of parameters in men whose couples conceived within 12 months. These figures are useful as a guide for interpreting the analysis, but it is emphasized that the lower 5th percentile does not constitute a "line" between fertility and infertility. [17]

Ejaculate volume depends on the duration of abstinence, the degree of arousal, hydration, frequency of ejaculations, and glandular activity. Therefore, "little" or "lots" are assessed not based on a single situation, but on repeated observations and in the context of other parameters, including acidity and the presence of sperm. [18]

The appearance also varies. The hue is usually whitish or grayish; a more pronounced yellowish tint may be associated with urine contamination, age-related changes, certain medications, or inflammation. A reddish, pink, or brown hue most often indicates blood, and although the cause is often benign, if it recurs or is combined with other symptoms, an examination is necessary. [19]

The odor is described in various ways, and a "chlorine" or "ammonia" tint can occur due to the alkaline reaction and the composition of volatile compounds. Another important point: a sharp, unpleasant, "fishy," or putrid odor, especially accompanied by pain, urethral discharge, or a burning sensation, is more alarming in favor of infection and requires an in-person evaluation. [20]

Table 4. Distribution guidelines for spermogram parameters in men conceiving within 12 months

Indicator	5th percentile	Median
Ejaculate volume, ml	1.4	3.0
Sperm concentration, million per 1 ml	16	66
Total sperm count, million per ejaculate	39	210
Total mobility, %	42	64
Progressive mobility, %	30	55
Viability, %	54	78
Normal forms, %	4	14

The table is compiled using distribution data from the World Health Organization guidelines. [21]

Table 5. Color changes and impurities: common causes and when to be concerned

Observation	Possible explanations	When to see a doctor
Yellowish tint	Urine impurities, medications, age-related changes, inflammation	If it persists, there is pain, fever, and an unpleasant odor.
Pink, red, brown shade	Blood in semen	If it recurs, there is blood in the urine, pain, fever, age over 40 years or risk factors
Green tint	Possible infection	As soon as possible if symptoms of inflammation appear

General guidelines for color changes and the significance of blood in semen are provided in clinical reference materials from major medical organizations. [22]

How long do sperm live and what does it depend on?

Sperm can remain viable within the female reproductive tract for several days. The most commonly reported range is around 3-5 days, especially if intercourse occurred near ovulation and cervical mucus "supports" the sperm during this period. [23]

However, this doesn't mean "always 5 days." Survival depends on sperm quality, the condition of the cervical mucus, the presence of inflammation, the time before ovulation, and many other factors. Therefore, calendar-based contraceptive methods have limitations: ovulation can shift, and sperm sometimes "survive" until the moment the egg is released. [24]

Outside the body, conditions are much harsher. When sperm dry out, they quickly lose motility, while in a humid environment, their survival time is longer, but still limited. In practical terms, this means the risk of pregnancy from sperm contact with skin is extremely low, whereas the risk arises from sperm entering the vagina. [25]

It's important to distinguish between "viability" and "the ability to fertilize." Even if a cell is formally alive, it can lose key functions, and the ability to fertilize is largely dependent on whether it has undergone the correct stages of "preparation" in the female reproductive tract. [26]

Table 6. Estimated sperm survival under different conditions

Wednesday	Typical order of magnitude	Comment
Female genital tract with favorable mucus	Up to 5 days	A frequently cited clinical landmark
Outside the body when dry	Minutes to hours	Rapid decrease in mobility
In laboratory conditions of storage and cryopreservation	A very long time with the right technology	A separate topic of reproductive medicine

Estimates of survival in the female reproductive tract are provided in clinical literature and reviews of reproduction.[27]

When is a spermogram needed and how to take the test correctly?

A spermogram is a basic test for assessing male factor infertility, as well as for certain complaints and situations where there is a suspicion of dysfunction of the gonads or patency of the vas deferens. However, even a "perfect" spermogram does not guarantee pregnancy, and conversely, moderate deviations do not always rule out natural conception. [28]

Results vary greatly depending on how the sample is collected and how quickly it reaches the laboratory. Standardization of the time before analysis is important: for example, macroscopic parameters are assessed after liquefaction, while liquefaction itself typically occurs within 15-30 minutes, with deviations noted if the process is delayed. [29]

In the case of abnormal results, a repeat test is usually recommended, as variability is high, and a single result may reflect temporary factors such as a recent infection, fever, stress, sleep disturbances, alcohol, overheating, or changes in ejaculation frequency. European clinical guidelines clearly state that, with normal results, one test is usually sufficient, while in the case of abnormal results, at least two studies are advisable. [30]

Interpretation must be "multiparametric." The assessment is not limited to a single number, as volume, concentration, motility, morphology, viability, and sometimes additional tests as indicated, such as repeated pregnancy losses or assisted reproductive technology failures, are all important. [31]

If the goal is not simply to "understand the numbers" but to improve the chances of conception, then the strategy depends on the underlying cause. In some cases, treatment of varicocele, correction of hormonal imbalances, or treatment of inflammatory processes can help. Therefore, a spermogram is the beginning of the journey, not the final diagnosis. [32]

Safety and myths: can you "treat yourself with sperm"? Risks of infection and allergies

The idea of "sperm therapy" in the form of application to the skin or oral administration has no evidence base as a medical method. Moreover, contact with sperm can be associated with real risks, primarily the transmission of infections during unprotected sex, including the human immunodeficiency virus, which is transmitted through certain bodily fluids, including semen. [33]

Sexually transmitted infections (STIs) are more than just "symptoms and discharge." In some people, they are asymptomatic, but they can still impact sperm parameters and reproductive outcomes. Therefore, if an infection is suspected, it is important to undergo testing and treatment according to standards, rather than attempting to "self-correct" with supplements. [34]

There's also a rare but important issue: an allergy to seminal plasma proteins, which can manifest as local symptoms immediately after exposure or even systemic reactions. This condition is described in modern reviews as rare, often underdiagnosed, and requiring proper diagnosis and management, especially if the couple is planning a pregnancy. [35]

Reasons for an in-person visit are usually considered to be recurring blood in semen, severe pain, fever, urinary problems, sudden changes in odor or color, as well as situations where pregnancy does not occur within 12 months of regular unprotected sexual intercourse. In such cases, a comprehensive couple examination, in which a spermogram is only one step, is logical. [36]