Apoptosis as a Normal Mechanism of Growth Control and Target of Toxicant Actions during Spermatogenesis

Abstract

Production and development of mature male gametes is essential for normal reproductive efficiency and survival of species. Epidemiological research and observations of wildlife have reported an increase in male reproductive abnormalities, including declining sperm counts in human males, thus opening a debate as to the role of environmental pollutants and other factors. The complex organization of the testis of man and common laboratory mammals, and the lack of a good in vitro spermatogenesis system for direct study, has hampered routine chemical testing and frustrated attempts to define the extent of the problem. The challenge is further exacerbated by our incomplete understanding of normal testicular control mechanisms, despite intense research activity over the last 25 years and the acquisition of powerful new tools of cellular and molecular biology for accumulating data. Future progress in understanding human health effects, and the impact of environmental factors on survival of species and ecosystems, has been linked to the development of new animal models and test systems.