A single low cadmium dose causes failure of spermiation in the rat

Ten-week-old male Sprague-Dawley rats were injected ip with cadmium chloride solution in a single dose of 0, 0.5, or 1.0 mg/kg body wt. At 4, 24, 48, and 72 hr after injection, testes of the animals were perfusion fixed, embedded in plastic, and sectioned. Tissue sections were stained and examined under the light microscope. These amounts of cadmium did not result in visible vascular lesion in the testes. However, at a dose of 1 mg/kg, the cadmium treatment resulted in failure of spermiation from stage IX through later stages of spermatogenesis in the seminiferous epithelium. Detailed statistical analysis revealed failed spermiation 24 hr after dosing. As the exposure time increased, failure of spermiation was observed with increasing frequency within an affected stage, and was seen at later stages of spermatogenesis as well. Testes of the rats treated with a cadmium chloride dose of 0.5 mg/kg showed no change in the frequencies of tubules having unreleased spermatids when compared to the controls. There was no difference in the stage frequencies between all the treatment groups and the controls. These results indicate that a single cadmium chloride dose of 1 mg/kg results in failed spermiation in rat seminiferous tubules, without discernible change to the surrounding endothelium. We conclude that cadmium begins to act during early stage VIII of spermatogenesis to induce failure of spermiation, and the action of cadmium is spermatogenic stage-specific.