1, semen volume: normal ≥ 2ml. more than 7ml is too much, not only the sperm density is reduced, and easy to flow from the vagina, so that the total number of sperm is reduced, commonly due to vesiculitis; less than 2ml is too little semen, but usually less than 1ml is too little. This is because of the small contact area between the semen and the female genital tract, or because the viscous consistency is not conducive to the entry of sperm into the female cervical opening and leads to infertility, commonly due to severe paraphimosis, low testosterone levels, ejaculatory duct obstruction, retrograde ejaculation, etc. 2, color: normal is gray or slightly yellow, milky white or yellow-green suggests the presence of inflammation in the reproductive tract or the secondary gonads; pink, red, microscopic red cells are seen as hemorrhagic semen, common in the secondary gonads, inflammation of the posterior urethra, occasionally seen in tuberculosis or tumors. 3. pH: The normal pH of semen is 7.2~7.8. Less than 7.2 can be seen in ejaculatory duct obstruction or contamination by urine; greater than 7.8 can be seen in inflammation of seminal vesicles or old specimens. 4, liquefaction time: normal semen after ejaculation, under the action of seminal vesicle coagulation enzyme into jelly, after 15-30 minutes under the action of prostatic liquefaction enzyme into liquid, this is the semen liquefaction, ejaculate 30 minutes after the semen, semen still does not liquefy belong to abnormal. 5.Viscosity: Touch the glass rod to the liquefied semen and gently lift it to form semen filaments. 6.Sperm count: Generally, the number of sperm per ml of semen is expressed. The normal count is ≥20×106/ml. Below this value is too little sperm, which can be seen in various causes of sperm dysfunction, which can lead to low fertility or infertility due to reduced chances of sperm entering the uterine cavity and fallopian tubes. If the sperm count is greater than 250×106/ml, the sperm count is too much, which can also lead to infertility due to the influence of its motility. 7, survival rate: usually refers to the examination within 1 hour after ejaculation, live sperm ≥ 50%. The common causes of reduced sperm motility and viability are paraphimosis, varicocele, chronic respiratory infection caused by cilia sluggishness syndrome, the presence of anti-sperm antibodies in semen or improper storage of specimens for routine examination and normal values. 8, motility: more than 50% belong to a and b grade (according to the quality of semen in the order of a. b, c, d. 9, leukocytes: normal semen leukocytes < 1 × 106/ml. Increased leukocytes indicate the presence of infection in the reproductive tract or paraphilic gonads. Mammalian spermatogonia can proliferate and multiply as stem cells, generating new stem cells and capable of producing cells that undergo differentiation; this not only preserves the generations of stem cells themselves, but also produces a steady stream of differentiated cells, which in turn produce primary spermatogonia. As to how many mitotic divisions they undergo to produce primary spermatocytes, it varies from animal to animal. Except for the earliest spermatogonia, the cytoplasm is not completely separated after each mitotic division during spermatogenesis, and the cells are connected by intercellular bridges, resembling syncytia. This may facilitate the maintenance of strict synchronization between cells and the simultaneous production of a large number of spermatozoa. After spermatocytes are produced, they enter the growth phase and increase in size, at which time they are called primary spermatocytes. Their nuclei synthesize DNA and their chromatin undergoes a complex series of changes in preparation for the first mature division (see meiosis). After division, each primary spermatocyte gives rise to two haploid secondary spermatocytes. The latter do not replicate DNA and, after a relatively short stay, enter into a second maturation division, forming two spermatocytes. Thus, a primary spermatocyte undergoes two maturation divisions to form four haploid spermatocytes. Only this stage is broadly similar in the spermatogenesis of various animals.