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.

Association of age with the threshold for detecting ankle inversion and eversion in upright stance.

A randomized quadruple staircase method and probit analysis were used to measure the thresholds for sensation of ankle inversion and eversion by 18 healthy young and 18 healthy old subjects while standing with a foot in a servo-driven cradle. The results of over 3600 trials show that the mean threshold for detecting inversion with a probability of 75% was 0.35 degrees in the older subjects, a value significantly greater than the 0.06 degrees threshold found in the younger group. The corresponding thresholds in eversion were significantly greater in both old (0.52 degrees) and young (0.35 degrees) subjects. Significant, but smaller, age differences were also found in unipedal stance. Few significant sex differences were found. When the velocity of a 0.1 degree inversion movement was increased from 2 to 200 degrees/s the probability of detecting it rose by only 22.6%. Although significantly increased with age, the threshold for sensing rotation in the weight-bearing ankle was measured in tenths of degrees, an order of magnitude better than previously reported (non-weight-bearing) values.