The influence of lead and manganese on spermatozoa of Eisenia fetida (Oligochaeta)

The effects of lead and manganese on the spermatozoan ultrastructure of Eisenia fetida were studied by feeding pre-clitellate worms in laboratory cultures weekly with fresh, urine-free cattle manure containing sublethal quantities of the heavy metal compounds for 8 weeks. The worms were analysed for heavy metal content after eight weeks, and electron microscopical observations of spermatozoa of exposed and control worms were performed. The body loads of heavy metals in the worms at the end of the observation period were 41.8 μg g−1 (0.20 μmol g−1) and 9.3 μg g−1 (0.17 μmol g−1) for Pb and Mn respectively, possibly indicating differential accumulation of the two metals since higher dosages of Pb were given. Electron microscopical observations showed marked cellular damage to the spermatozoa from worms exposed to the heavy metals, compared to the sperm cells from the control worms. Structural damage of spermatozoa included breakage and loss of nuclear and flagellar membranes, thickening of membranes, malformed acrosomes and loss of nuclear material. The fact that the spermatozoa were adversely affected by sublethal concentrations of certain heavy metals, raises the possibility of utilizing this phenomenon in toxicity testing.