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Introduction to Epidemiology

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Epidemiology, known as the cornerstone of public health, involves studying the distribution and determinants of health-related events in defined populations and applying these insights to control health issues. This is essential for understanding how diseases spread, identifying populations at greater risk, and implementing measures to control or prevent outbreaks. Epidemiology addresses not only infectious diseases but also non-communicable conditions like cancer and cardiovascular disease,...

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Sperm Structure and Semen Composition

Sperm Structure and Semen Composition

During ejaculation, males release around 2-5 milliliters of semen, which is a complex mixture of mature sperm and various fluids produced by accessory glands. The mature sperm cells measure approximately 60 micrometers in length and consist of a head, neck, midpiece, and tail. The head is flattened and tapered, measuring about 4 to 5 micrometers in length. It contains a nucleus with condensed chromosomes and an acrosome, a cap-like structure filled with enzymes essential for penetrating the...

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Updated: Jun 16, 2026

The Examination of Peroxidase-Positive Leukocytes in Semen

The Examination of Peroxidase-Positive Leukocytes in Semen

Published on: January 19, 2024

Semen analysis from an epidemiologic perspective.

Jens Peter Ellekilde Bonde¹

¹Department of Environmental and Occupational Medicine, Copenhagen University Hospital, Denmark. jpb@bbh.regionh.dk

Asian Journal of Andrology

|January 30, 2010

Summary

The World Health Organization (WHO) now provides reference values for semen analysis. However, these values have limited use in epidemiological research investigating environmental impacts on male reproductive health.

Area of Science:

Reproductive Health
Environmental Epidemiology
Andrology

Background:

The latest World Health Organization (WHO) manual for semen analysis introduces reference values for human semen characteristics.
This development occurs amidst ongoing debates regarding temporal and geographical variations in sperm counts.
Concerns persist about the potential adverse effects of anthropogenic chemicals on male reproductive health.

Purpose of the Study:

To evaluate the utility of the new WHO semen analysis reference values in addressing debates on sperm count trends.
To assess the role of these reference values in investigating hypotheses linking environmental chemical exposure to male reproductive health issues.
To explain the limitations of these reference values for specific research purposes.

Main Methods:

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Last Updated: Jun 16, 2026

The Examination of Peroxidase-Positive Leukocytes in Semen

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Avian Semen Collection by Cloacal Massage and Isolation of DNA from Sperm

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Published on: February 5, 2018

Critical review of the implications of the new WHO semen analysis reference values.
Analysis of the applicability of reference values in epidemiological research.
Discussion of the role of semen analysis in reproductive health research.

Main Results:

The established reference values for semen characteristics are of limited utility in analytical epidemiologic research.
The WHO guidelines are crucial for developing appropriate research protocols.
Semen analysis remains a valuable, albeit imperfect, research tool in epidemiology.

Conclusions:

The new WHO semen analysis reference values are unlikely to resolve debates on sperm count trends or environmental impacts.
Despite limitations, WHO guidelines are vital for standardizing research protocols.
Semen analysis continues to be an important tool for epidemiological research in male reproductive health.