Organism-level effects mechanisms of reproductive toxicology

4 Organism-level effects mechanisms of reproductive toxicology 

The effects of endocrine disrupters have clearly indicated that exposure at low concentrations during critical windows of exposure can have a severe impact on 

Within an ecotoxicological perspective, mammalian methods cannot be extrapolated automatically to other species. Sperm of teleosts, for example, differs in a few very important aspects from that of mammals. Unlike mammalian sperm it is not motile on ejaculation and attains motility only on contact with water. After activation it only moves for a few minutes (for freshwater fish typically around 1 min). Furthermore it enters the egg via the micropyle rather than through an acrosomal reaction. The first minute after the start of motility is therefore crucial to its success in fertilizing an egg, and even when it is deposited on the egg s surface it still has to move fast enough in the right direction to reach the micropyle. Clearly the fertilizing ability of fish sperm is very dependent on its motility, and any pollutant that decreases this movement may be expected to affect fertilization. 

Successful reproduction is clearly essential for the propagation of every species, prerequisites for which are high quality and properly functioning gametes. Spermatozoa, however, are known to be very sensitive to environmental pollution, as shown in studies by Billard and Roubaud (1985), Khan and Weis (1987a,b), Anderson et al. (1991), Rurangwa (1999), and Van Look (2001). The motility of fish sperm can be affected by pollutants in several ways (1) by alteration of the 

Because sperm may be held immotile in an extender for up to 24 h without significant loss of quality (Kime et al., 1996 Rurangwa et al., 1998), it is possible 

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