Semen and Nocturnal Ejaculation
1. Semen and Sperm. Semen consists of seminal plasma and sperm suspended in it. Sperm is produced in the testes. In semen, 5% is sperm and 95% is seminal plasma. Seminal plasma is a mixture of secretions from the epididymis, seminal vesicles, vas deferens, prostate, bulbourethral glands, and reticulum testis fluid.
Semen commonly appears in four colors: grayish-white, milky white, pale yellow, and brownish-red. A darker pale yellow usually indicates a longer interval between ejaculations. Brownish-red indicates hematospermia, which is likely caused by inflammation of the reproductive tract or seminal vesiculitis. Semen has a distinctive fishy odor. A precise pH test strip can be used to measure it between 5.5 and 9.0. Normal pH is 7.0 to 7.8. If the pH is <7 or >9, sperm motility is significantly reduced. Freshly ejaculated semen is relatively viscous and gelatinous, liquefying into a thin liquid after 10–30 minutes. Thick semen, when examined under a microscope immediately, will show slowly motile sperm. Semen that does not liquefy within one hour at 25°C is considered abnormal. Normal ejaculation volume is 2–6 ml, with an average of 3.5 ml. However, the frequency of ejaculation is closely related to semen volume. Less than 1.5 ml or more than 8 ml is considered abnormal.
Male fertility is primarily determined through semen analysis. Semen analysis results are affected by factors such as the frequency of ejaculation, temperature, pH, and chemical substances, all of which can alter sperm count and motility. For semen collection, abstinence for 3–7 days is required, including nocturnal emissions and masturbation; the sample should not be older than 3 hours.
Before the discovery of sperm, some Western scholars imagined that various “little people” might exist in semen, which, during intercourse, would be introduced into the mother’s body and develop into a fetus. In November 1673, Dutch scholar Levenhoek, using his newly invented microscope, observed human sperm for the first time. This unprecedented discovery shocked the scientific community. King Charles II of England also personally observed sperm under the microscope. When he saw the unusually active and freely swimming human sperm, he excitedly said, “Its shape is like a newborn tadpole, with a large head and a long tail, and it moves nimbly.”
Sperm is one of the smallest cells in the human body. A normal sperm cell consists of three parts: head, body, and tail. The head is pear-shaped or oval, 4.5 μm long and 3 μm wide, thick and flattened at the back, the middle section (body) is 7–8 μm long, and the tail extends to 45 μm. Human sperm morphology varies greatly; common abnormal sperm include those with large heads, small heads, amorphous heads, double heads, double tails, and coiled tails. Sperm density is directly related to male fertility. Of 20 million motile sperm, only about 200 will reach the fallopian tubes. Foreign data reports significant variation in sperm count, with normal male sperm counts ranging from 20 million to 200 million/ml. Domestic reports indicate that among 365 fertile men, 95% had sperm densities between 10 million and 180 million/ml; 51% had densities greater than 60 million/ml; and 1% had densities less than 10 million/ml. The lowest density was 4 million/ml (1 case), and the highest was 396 million/ml. Of course, assessing male fertility cannot rely solely on semen analysis; it requires analysis of sperm count, motility (viability and activity), the time between semen analyses, sperm abnormality rate, semen viscosity, and viability. Sperm motility refers to their ability to survive outside the body. The length of survival and the quality of motility indicate sperm quality. Data from my country indicates that normal sperm motility is ≥60% 1 hour after ejaculation; ≥40%–50% 3 hours after ejaculation; and ≥20%–30% 6 hours after ejaculation.
Morale is as follows:
There is no significant difference between 1 hour and 3 hours, with Grade III motility sperm accounting for 50%–40%;
At 6 hours, Grade III motility sperm accounts for only 15%–10%;
If no motility sperm is visible after 6 hours or the grade drops to 5%, fertility may be affected.
