Male Infertility : Causes, Diagnosis and Treatment
Urology / / August 12, 2017
Infertility - the inability to couple conceive after one year of regular, unprotected intercourse protection.About one-third of infertility problems due to the infertility of women, another third - infertile men.In other cases, the cause of infertility is not clear.
male reproductive system
male reproductive system produces sperm (semen, ejaculate), which is produced in the seminiferous tubules within each testicle.The head of the sperm - the male reproductive cells, which serves to fertilize a female egg - containing DNA (deoxyribonucleic acid), which is due to the combination with the DNA of the egg conceived a new man.The tip of the sperm head is a part called the "acrosome", which allows the sperm to penetrate the egg.The middle (the middle part - the neck, body) of the sperm contains mitochondria (organelles the size of a bacterium), which supply energy to the tail (flagellum) of sperm.This tail (flagellum) with a whip has to move back and forth, pushing the sperm towards the egg.The sperm ha
Male fertility (the body's ability to participate in male fertilization) is dependent on the proper functioning of the following complex systems of organs and hormones:
- the process starts in the brain called the "hypothalamus".There is a so-called "axis of the hypothalamus-pituitary-testes" (hypothalamic-pituitary-gonadal system) - hormonal interconnected system organs: pituitary glands system, hormones and chemical messengers - neurotransmitters.All these bodies are essential for the reproduction of human beings;
- the hypothalamus produces gonadotropin-releasing hormone, or gonadorelin, GnRH, gonadotropin-releasing factor (GnRH), which causes the pituitary gland to produce follicle stimulating hormone (FSH) and luteinizing hormone (LH);
- FSH maintains sperm production, and LH stimulates the production of the male hormone testosterone;
- production of sperm and testosterone occurs in two testicles, which are contained in the scrotum - the pouch on the outside of the body (core body temperature is too high to allow to produce sperm).
Male reproductive structure includes: the penis, scrotum, seminal vesicles and prostate gland (prostatitis).
- Cum . Sperm is produced in hundreds of microscopic tubes known as "seminiferous tubules", which make up most of the testicles.Surrounding these tubules clumps of tissue containing hormone producing Leydig cells, which produce (synthesize) testosterone when LH stimulation.
- sperm production (spermatogenesis) . life cycle of sperm takes approximately 74 days:
- sperm begins to partially integrated into forming the lower part of the wall of the convoluted seminiferous tubules Sertoli cells (sustentotsity supporting cells).These cells form a tissue containing spermatogonia and spermatocytes;
- when the sperm matures and moves forward, it is stored in the upper part of the seminiferous tubules.Young sperm cells called "spermatid";
- when the head and tail of the sperm mature, sperm must be released from the cell into the epididymis, a C-shaped long pipe.Then the sperm moves back and forth in a very small space.The path of sperm through the appendage takes about 3 weeks.
liquid in which a sperm is transported, in the form of sugar comprises fructose, which provides energy for sperm maturation.In the early stages of the passage of the fluid, the sperm can not swim in the forward direction, and can only faintly vibrate its tail.When the sperm reaches the end of the epididymis, it is mature and looks like a microscopic curving tadpole.
Every mature and healthy sperm consists of a head, which contains the genetic material (DNA) of a man and the tail, which moves back and forth at high speed, every second advancing head forward over a distance of approximately four times greater than his ownlength.The ability of sperm to move forward quickly and directly - probably the most significant factor determining male fertility.
- Ejaculation . Ejaculation - the last stage of the sexual act, in which there is an allocation from the urethra semen (during sexual intercourse or other forms of sexual activity).
When a man experiences sexual excitement, nerves stimulate his muscles in the epididymis, causing the sperm to pass through the penis.After production in the testis, sperm first passes through the appendage, and then through one of the two muscle hard wired channel (one channel of the pair is called "vas deferens" - a tube that transport semen).
muscle contractions in the vas deferens from sexual activity by promoting sperm seminal vesicles - a kind of tissue clusters, producing seminal fluid in semen.The vas deferens is also going fluid from neighboring glands - a mixture of different fluids and semen.
Each of the vas deferens then joins the others that together form the ejaculatory duct.This channel, which now carries the spermatozoa contained in semen, passes down through the urethra (this is the urethra and the same channel in the penis through which a man urinates. During orgasm muscles block the bladder so that urine can not enter into the urethra).
semen passes through the urethra during ejaculation - the final stage of orgasm when the sperm are literally thrown out of the penis.
- Seminal fluid. In addition to providing the genitourinary system with fluid that transports sperm, semen also has other advantages:
- she very briefly provides an alkaline environment that helps protect sperm from the strong acidity of the female vagina (if the sperm reaches the neck of the woman uterus for severalhours, sperm becomes toxic and dies);
- it contains a gelatinous substance, which prevents too rapid discharge of semen from the vagina;
- it contains sugar in the form of fructose, which helps to provide instant energy for sperm movement.
- The path to the egg. passage of sperm to the egg is difficult "journey."Usually about 100-300 million sperm constitute ejaculate (semen) at any time.But even under normal conditions only about 15% of these millions of sperm able to fertilize the egg.
After ejaculation, only about 400 thousand sperm experiencing orgasm and can continue the journey.Of these, only about 40 sperm survive from the problems associated with sperm characteristics and with the surrounding environment of the vagina and women seek to achieve proximity to the egg.Typically, cervical mucus (discharge from the uterus, making it possible to determine the onset of ovulation) forms an impenetrable barrier to sperm.However, when a woman is ovulating (releasing the ovary into the abdominal cavity of a mature and able to fertilize an egg), the ovary mucous membranes become thinner, allowing the penetration of sperm into the egg.
sperm that "failed" to reach the mucosa in the cervix of women must survive 4 days or more to reach the fallopian tubes of women (where the egg is able to fertilize only 12 hours a month).
Few remaining sperm penetrate the cervical mucus and able to reach the fallopian tubes, are capacitated.Capacitation, when the uterine environment has an activating effect on sperm motility and increases noticeably, - a one-time burst of energy, completing the journey of sperm.sperm movement speeds, which causes action acrosome - reminiscent warhead membrane vesicles bearing the egg shell dissolving lytic enzymes.Acrosome, sperm head covering, dissolve, and enzymes contained in them is released.Then the sperm drills a hole in the outer shell of the ovary.In the end, a single sexual act in the best case, only one sperm penetrates the fertilized egg.
Causes of male infertility
More than 90% of cases of male infertility due to low sperm count, poor sperm quality, or both, both.The remaining cases of male infertility caused by a number of the following factors, including anatomic problems, hormonal imbalances and genetic defects:
- sperm abnormalities. sperm abnormalities may be caused by a number of factors, including birth defects, diseases, chemical exposure, and certain lifestyle.In many cases, the causes are unknown sperm abnormalities.
sperm anomalies are classified according to whether they affect the number of sperm, their shape or movement.These anomalies may be as follows:
- oligospermia - an abnormally low concentration (amount) of sperm in the semen (ejaculate).Number of at least 20 million sperm / ml - low volume of semen;
- azoospermia - a complete absence of sperm in the ejaculate.Any partially enclosed area in long passageways, through which the spermatozoa could reduce their number.Sperm count varies widely over time, and the time low levels are common.However, one test showing a low volume of semen can not be recognized for the overall result;
- asthenospermia - poor motility, with a low number of motile sperm.Sperm motility - that is their ability to move.If the motion is slow or is not in a straight line, then the sperm is difficult to invade the cervical mucus, or to penetrate the hard outer shell of the ovary.If 60% or more are normal motility of spermatozoa, the sperm with at least medium quality.If less than 40% of the sperm is able to move in a straight line, it is considered abnormal.Sperm, which moves slowly, may have genetic or other defects that make it unable to fertilize an egg.Poor sperm motility may be associated with DNA fragmentation and may increase the risk of transmission of genetic diseases;
- teratospermia - morphology (form and structure) of abnormal sperm.Abnormal shaped sperm can not fertilize an egg.About 60% of the sperm should be normal size and shape for adequate fertility.Perfect sperm structure - oval head and a long tail (flagellum);
- Retrograde ejaculation. Retrograde ejaculation occurs when the bladder wall muscles do not function properly during orgasm, the sperm and does not move forward into the urethra, and back - and not in the testicles, and bladder.Semen quality is often violated in this case.
Retrograde ejaculation may be due to reasons such as:
- surgery at the bottom of the bladder or prostate (the most common cause of retrograde ejaculation);
- diseases such as diabetes and multiple sclerosis;
- injury or surgery of the spinal cord;
- drugs - such as alpha-blockers, used to treat enlarged glands, tranquilizers, some antipsychotics, blood pressure medications, etc .;
- Structural abnormalities. Any structural abnormalities that damage or block the testes, tubes or other reproductive structures can affect male fertility:
- cryptorchidism (undescended testicles) . Cryptorchidism - one of the congenital causes of male infertility.As a rule, it is most common in newborns.If cryptorchidism testes unable to descend from the abdomen into the scrotum.This problem leads to impaired sperm production;
- hypospadias. Hypospadias - also birth defects for which there is urinary opening on the underside of the penis.This can interfere with sperm to reach the cervix, if the problem is not corrected by surgery;
- Blockage of tubes of sperm transport. Some people are born with blocked tubes or other problems in the epididymis or urethral.All these problems subsequently affect male fertility.Some men do not have the vas deferens - the tube that carries sperm from the testicles through the penis.Mulock number of sperm in the ejaculate may be associated with structural abnormalities in the tubes through which sperm is transported;
- Hormonal deficiencies. Hypogonadism - is the common name of severe deficiency of gonadotropin-releasing hormone (GnRH) - the primary hormone that signals the process leading to the release of testosterone and other essential hormones.Low for any reason testosterone levels can lead to faulty sperm production.Hypogonadism is rare and usually occurs at the time of birth.It is usually the result of rare genetic diseases that affect the pituitary - such as for example: selective disadvantages hormones FSH and LH, Kallmann syndrome (secondary hypogonadotropic hypogonadism occurs when panhypopituitarism).Hypogonadism may also develop later in life from a brain tumor or pituitary gland, and - as a result of radiation therapy;
- Genetic diseases. Some inherited disorders may impair male fertility.Examples include:
- cystic fibrosis, for which may be missing or broken vas deferens;
- polycystic kidney disease - a relatively common genetic disorder that causes large cysts in the kidneys and other organs during adulthood, and that can lead to infertility if cysts develop in the genital tract;
- syndrome Klinefelter - several types polysomy on chromosomes X and Y in men is most often marked by two X and one Y chromosome (the norm - one X and one Y chromosome) causes low testosterone levels and abnormalities of the seminiferous tubules, although most other physicalwherein the functions normally;
- Kartagener's syndrome - a rare disease that causes violation of sperm motility, as well as serious infections of the respiratory tract and the reverse (mirror) the location of the major internal organs.
Risk factors for male infertility
- varicocele.It veins grozdevidnogo plexus of the spermatic cord, is abnormally enlarged, twisted veins in the spermatic cord, which is connected to the testicles.Varicocele has about 15% of all men and 40% of infertile men, although it is not clear whether this defect affects fertility or any mechanisms.When varicocele testicular temperature may rise, which could have implications for the production, movement and shape of sperm.
- Age. Age-related changes in semen of men - is a gradual process.Aging can affect the quality and sperm motility (its ability to swim quickly and move in a straight line).The genetic quality of sperm decreases with the age of the person.
- Sexually transmitted diseases. Repeated infections chlamydia or gonorrhea - a sexually transmitted disease that is most often associated with male infertility.These infections can cause scarring and blocking passage of sperm.Infection (infection) human papillomavirus (HPV) - the causes of genital warts - can also impair the function of the sperm.
- Lifestyle factors. Almost any major physical or mental stress can temporarily reduce sperm count.Some common conditions that lower sperm count, temporarily in nearly all cases, include:
- overheating of the testicles.Overheating of, for example, high body temperature, saunas, hot tubs, may temporarily reduce the number of sperm;
- substance abuse and addiction.Intensive use any hard drugs, including cocaine or marijuana may temporarily reduce the number and quality of sperm.The use of anabolic steroids can reduce the testicles and lower sperm production.