Does cadmium cause more damage to the sperm neck than other sperm areas?

Dear Editor: The men's reproductive impairment following exposure to heavy metals is one of the most serious concerns in to-day's industrial societies. Heavy metals are responsible for invasive injuries to the male reproductive system at the cellular and structural levels. One of Heavy metals is cadmium that release through industrial activity in the form of cadmium oxide, cadmium chloride, or cadmium sulphide into environment (۱). Many studies have shown the effects of cadmium toxicity on testicular and sperm parameters (۲-۴). In a recent our study with doses of ۲ and ۴ mg/kg in adult male rats, we found that high percentage of sperm from the neck region was divided into two segments, which was directly related to the cadmium dose. This observation leads to the question that, why injury to sperms occurs from the neck region? Does the neck region have a specific molecular and cellu-lar structure that is sensitive to cadmium? Undoubtedly, answering this question without designing and perform-ing in vitro studies in order to investigate the relation-ship between molecular and cellular structure of the sperm neck and cadmium toxicity is not feasible. If this question is answered, it's a very important point in coun-teracting the cadmium toxicity for sperm. Therefore, a study design to investigate this relationship is recom-mended.