Semen (human)

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Human semen is the "seed" of mankind, the mix of body fluids and male gametes (spermatazoons), that, when deposited in the female reproductive tract, can result in fertilization of an egg. Evaluation of semen is a standard part of the medical work-up for infertility.

Characteristics of normal semen

Certain characteristics of semen are considered important , or evaluating a sample from a potential donor for artificial insemnation.

  • WHO criteria include sperm concentration, percentage motility, and morphology.
  • Kruger's strict criteria include: curvilinear velocity (VCL), straight line velocity (VSL), average path velocity (VAP), lateral head displacement (ALH), linearity

Fertility in men

Male fertility is intimately related to the quality and quantity of sperm cells in semen. At present, when men are evaluated for infertility, semen samples are routinely collected and examined.

Infertility in men

At a minimum, a failure to establish a pregnancy within 1 year of unprotected intercourse is required before a man is considered a candidate to be evaluated for infertility. Perhaps the most widely utilized semen characteristic is sperm count. Men with less than 20 × 106 spermatozoa/mL are typically deemed subfertile, and men with counts less than 5 × 106 spermatozoa/mL are often considered to be infertile[1].

In some cases of male infertility, there are strategies that can overcome problems in sperm number or quality and allow a successful preganancy. In other cases, a sperm donor may be sought in order to establish pregnancy.


Varicocele is a condition of an enlarged and excessively twisting course of the veins within the spermatic cord (pampiniform plexus). Although some men with this condition are fertile, varicocele is a cause of infertility in many men.

  • seminal oxidative stress levels (ROS-TAC score)


  1. A. Agarwal, R.K. Sharma and D.R. Nelson. 2003. New semen quality scores developed by principal component analysis of semen characteristics, J Androl; vol. 24, pp. 343–352