There are more causes of low sperm motility. In summary, the main categories are as follows.
1.Infection
Acute and chronic inflammation of the reproductive tract or reproductive glands such as the epididymis, vas deferens, seminal vesicles and prostate can reduce the motility of sperm. The effect of infection on sperm motility can be multifaceted. The direct effect of microorganisms on sperm, such as mycoplasma, can attach to the head, mid-section and tail of sperm, causing increased hydrodynamic resistance and slower movement when sperm make forward motion, affecting sperm viability and the ability to penetrate egg cells. In addition, mycoplasma can cause partial sperm membrane defects or even membrane structure destruction, affecting the fertilization ability of sperm. E. coli can reduce sperm viability by binding to sperm through its own receptors; the indirect effect of microorganisms on sperm can be through the production or release of toxic substances, and mycoplasma produces NH3 during growth to have a direct toxic effect on sperm. Escherichia coli can produce sperm braking factor. Decreased sperm viability due to infection can also be achieved by changing the pH of seminal plasma, which decreases significantly when the pH is below 7 or above 9. In patients with acute adnexal inflammation or epididymitis, the pH is more alkaline, while chronic adnexal inflammation can cause the pH to fall below 7. In addition, inflammation-induced leukocytosis in semen can lead to a decrease in sperm motility through direct and indirect causes. The lack of sperm motility caused by prostatitis may be the result of a combination of factors, which may be related to zinc disorders in addition to microorganisms, leukocytes, pH, etc.
2, abnormal semen liquefaction
The non-liquefaction or high viscosity of semen is one of the causes of male infertility, and one of the very important factors may be the infertility by affecting the motility of sperm. In seminal plasma with non-liquefied semen, elongated fibrin may be seen and intermeshed to reduce the space for sperm movement, and sperm are held back, while coarse fibers are seen connected by many fine fibers in a network, which may be responsible for mechanically limiting forward movement of sperm. The authors of this paper have used urokinase-type fibrinogen activator (uPA) alone on specimens of non-liquefied semen in vitro and found that when semen changed from non-liquefied to liquefied state, sperm viability and forward motility increased significantly, and the same effect was obtained with chymotrypsin.
3. Immunological factors
Anti-sperm antibodies (AsAb) can affect the fertilization function of sperm in several different ways. The effect on sperm viability may be that AsAb binds to the tail of the sperm, which impedes sperm viability, reduces motility, and has poor penetration ability, which has been confirmed by a significant decrease in the ability to penetrate cervical mucus when anti-sperm antibodies are present against the tail of the sperm. Some scholars used AsAb-positive serum and human sperm contact and observed a so-called sperm “fluttering phenomenon”, mainly the head and the entire tail of sperm combined with anti-sperm antibodies, the forward motion of sperm was inhibited, but the survival rate did not change significantly.
4.Endocrine factors
In addition to the role of endocrine hormones on spermatogenesis and maturation, they also affect the motility of sperm. Gonzales et al. found that prolactin in seminal plasma has a linear relationship with sperm activity, which improves sperm oxygen uptake or affects sperm motility through the cAMP system, and reduces sperm motility when E2 levels in serum are elevated. Excessive testosterone in seminal plasma may inhibit sperm motility.
5. Kartagener’s syndrome
Kartagener’s syndrome was first identified by Kartagener in the early 1930s and was later confirmed by other scholars to be a congenital lack of ciliary structures, manifested by the inability to move cilia in various ciliated cells in the body, mainly the ciliary dynein arms of peripheral microtubules.
alms) of the peripheral microtubules is absent. Patients with this syndrome may have chronic respiratory infections traced from their medical history, in addition to the inability of sperm to move.
6. Chromosomal abnormalities
Autosomal and sex chromosome abnormalities affect sperm viability and forward motility, in addition to sperm count. The ultrastructural apparatus known to be associated with sperm motility can have abnormal sperm tail structure due to genetic factors, for example, lack of inner or outer branched arms or absence of both arms. There can also be a lack of central junctions and central complex structures, as the interaction between the central microtubules and the radial spokes can mediate the gliding of the outer microtubules, and when this structure is abnormal, sperm motility can be impaired.
7, Varicocele
Varicocele can cause male infertility in several ways, not only by affecting spermatogenesis, but also by causing a decrease in sperm motility. The mechanism may be due to blood stagnation in the varicose veins, impaired microcirculation, lack of nutrient supply and reduced partial pressure of oxygen, insufficient energy production and endocrine dysfunction. In addition, varicocele may also cause a decrease in sperm viability indirectly due to autoimmunity such as the production of anti-sperm antibodies and mycoplasma infection.
8.Other factors
(1) trace elements in seminal plasma zinc, copper, magnesium and semen quality, seminal plasma zinc content is more than 100 times the plasma content, low sperm vitality patients in the seminal plasma of zinc, iron, magnesium content is significantly lower than the vitality of normal healthy men. Zinc delays lipid oxidation of cell membranes and maintains the stability and permeability of cell structures, thus ensuring good sperm motility. Trace elements cadmium (Cd) content is high, can lead to reduced sperm motility, cadmium can directly inhibit sperm oxidase and direct inhibition of sperm motility organs, infertile men semen cadmium content significantly higher than fertile men.
(2) Lack of enzymes or reduced enzyme activity related to sperm motility, vitamin class deficiency, engaging in high temperature, radiation occupations and exposure to chemical toxins can all cause reduced sperm motility.
(3) Smoking, alcohol consumption and drug factors Nicotine in tobacco affects sperm motility through direct and indirect damage to sperm, long-term alcoholics can directly and indirectly affect sperm motility, and there are more drugs that affect sperm motility.
Weak spermatozoa are diagnosed mainly based on routine semen analysis and medical history questioning. Weak spermatozoa can be diagnosed after 3-7 d of abstinence followed by masturbation and more than 3 consecutive routine semen analyses suggesting less than 50% forward motion of sperm (class a+b) or less than 25% fast linear forward motion of sperm, sperm density greater than 20~106/mL, and other parameters normal or basically normal. Or 1h after ejaculation, sperm viability less than 50%, laboratory or other auxiliary examination can find reproductive tract infection, or other diseases that affect sperm viability, can be diagnosed as weak spermatozoa.