It has been noted that the sperm quality in humans is deteriorating in recent years. It could be related to the exposure of the fetus to chemicals that act as anti-androgenic agents and interfere with the development of normal sperm. Anogenital distance is a measurement used usually in animal studies to gauge the distance between the anus and the base of the penis, which is an indicator of male feminization and later reproductive problems. This study found that the same anatomical measure is linked to semen quality in young men attending university. After further research the anogenital distance could be used as important biomarker in human reproductive research and in clinical settings.
Development of the male reproductive tract in an embryo takes place under the influence of androgenic hormones. In experimental animals, environmental chemicals can interfere with androgen production and influence this development negatively. But establishing such links between anti-androgenic exposure in the uterus and its influence in humans is difficult. A measurement of the distance from the anus to the genitals is used in animal research. In rodents and other mammals, this distance is linked to the amount of androgen which a male fetus is exposed to in early development. This current study researches the link between the distance from the anus to the genitals and the quality of semen in young male students in a university.
* One-hundred-and-twenty-six young men from the University of Rochester participated in the study.
* The study included a physical examination, testing of blood, urine and semen samples, and answering a brief questionnaire.
* Semen was collected in the laboratory after a minimum of 48 hours of abstinence and the ejaculated sample was examined within 30 minutes.
* Two measurements of anogenital distance were recorded by a digital caliper. The first, AGDap, was measured from the insertion of the penis to the center of the anus. The second, AGDas, was measured from the first fold of the scrotum to the center of the anus.
* Though participants were apparently healthy young men, 24.6 percent of them had a sperm count below 20 x 106/ml, a commonly used cutoff for subfertility.
* AGDap measured from the insertion of the penis to the center of the anus had no relation to semen quality.
* AGDas measured from the first fold of the scrotum to the center of the anus was linked to semen quality .The risk of subfertility was increased 7.3 times for an AGDas below the median of 51.7mm, as compared with AGDas above the median.
* AGDas was positively related to sperm concentration, motility, morphology, total sperm count and total motile sperm count.
Shortcomings /Next Steps
The population studied is small and consisted of mainly healthy Caucasian men who where nonsmokers. This made the population limited in age and ethnicity and it might not provide normative values for AGD measurements. AGD measurement is used in animal toxicology studies to document intrauterine exposure to anti androgens. AGD measurements also vary with body size. Different AGD measurements may reflect androgen exposures at different stages of life, such as puberty. Also the semen quality report was based on a single sample from each participant.
In western populations, there is an increasing incidence of male reproductive disorders as well as decreasing sperm count and testosterone levels. A testicular dysgenesis syndrome (TDS) is hypothesized to be responsible for this. This syndrome is related to exposure to anti androgenic hormones during a critical period of development of male reproductive organs of the fetus in the mother’s uterus. The study showed that short ano-genital distance could be an important biomarker to determine human TDS. However, this study is based on a small population and a larger quantity of data needs to be obtained to determine the normative range of AGD. Also techniques such as ultrasonography need to be developed for recording AGD in fetus or infants.
For More Information:
Shorter Anogenital Distance Predicts Poorer Semen Quality in Young Men in Rochester, New York
Publication Journal: Environmental Health Perspectives, March 2011
By Jaime Mendiola; Richard W. Stahlhut; The School of Medicine and Dentistry, University of Rochester, Rochester, New York