Normal semen is a mixture of the secretions of the testes and epididymis and the sperm suspended therein, mixed with the secretions of the prostate, seminal vesicle and urethral bulb glands at the time of ejaculation. The final ejaculated mixture is a viscous fluid, i.e. the ejaculated semen is ejaculated in clumps in several successive ejaculations. A comparison before and after vasectomy shows that 90% in terms of volume is from the secretions of the accessory glands, mainly the prostate and seminal vesicle glands and to a lesser extent from the urethral bulb glands and epididymis.
Two main quantitative indicators of semen are.
1. Total sperm count, which reflects the spermatogenic status of the testes and the patency of the post-testicular ductal system.
2. Volume reflecting the secretory capacity of the glands.
Sperm function is mainly influenced by the vitality, motility, morphology and seminal plasma composition of spermatozoa themselves.
During intercourse, the initial sperm- and prostatic fluid-rich fraction of semen may come into contact with each other and the cervical mucus filaments that continue in the vagina, while the rest is formed while the entire semen is retained in a container during the experimental retention of the specimen, with the sperm confined in a clot caused by proteins secreted by the seminal vesicle glands and subsequently hydrolyzed by the action of enzymes secreted by the prostate.
There is evidence that the quality of semen samples varies with the method and location of sampling, with higher quality usually being retained at home by the intercourse method, suggesting that different methods of semen evacuation significantly affect the test results of the samples.
The quality of semen samples under fixed conditions is mainly influenced by the spermatogenic function of the testes, the secretion of the accessory glands, recent illnesses, especially hyperthermic illnesses, and others such as the duration of abstinence, which should be taken into account when interpreting the monitoring results.
The results of semen quality analysis are mainly influenced by the following factors.
1. the completeness of the sample collection. The semen in the front part rich in spermatozoa is avoided to be lost during ejaculation, while the back part of the semen is mainly composed of secretions from the seminal vesicle gland, so the loss of the front part of the semen has a greater impact on the semen analysis results than the loss of the back half.
2. During ejaculation, the secretion of the accessory glands dilutes the epididymal fluid containing a high concentration of sperm. The sperm concentration cannot directly reflect the sperm production of the testes because it is also affected by the function of other reproductive organs, while the total sperm count (sperm density X semen volume) sperm density does not differ for young and old people, but there may be differences in the total sperm count, and at least some people in the population have the phenomenon of declining semen volume and sperm with increasing age.
3. The viability and chromosomes of sperm are not affected by the length of abstinence, unless the function of the epididymis is affected. Because the previous ejaculation was not complete, the epididymis was not completely emptied and some sperm remained. Sperm aging can affect sperm quality, the extent of which is difficult to determine, so it is also rarely done for consideration.
4. The size of testicular volume not only reflects the sperm production level of the testes but also affects the total number of sperm and sperm morphology of each ejaculation.
According to the results of semen evaluation by the WHO recommended method, the semen composition changes over time.
This change suggests the following clarification of semen analysis.
1. The quality of sperm cannot be determined from just one semen examination.
2. Two to three examinations can help to obtain reliable basic data
Semen appearance.
Normal semen should have a homogeneous, off-white appearance after liquefaction.
If the sperm density is very low, the semen may appear somewhat transparent. If red blood cells are present, semen may appear reddish-brown; if the patient has jaundice or is taking certain vitamins, semen may appear yellow. The lower reference value for semen volume is 1.5 ml. The reference value for semen pH in fertile men has not yet been determined and is now kept at the original lower limit of 7.2. The lower reference value for sperm density is 15 x 106/ml. The lower reference limit for the percentage of total motile sperm is 40%; the lower reference limit for the percentage of actively motile sperm is 32%. The lower reference limit for the proportion of live sperm (cell membrane intact sperm) is 58%. The reference lower limit for morphological analysis of spermatozoa: the percentage of normal spermatozoa is 4%.