Testis response to low doses of cadmium in Wistar rats.

Although it is well known that cadmium (Cd) causes adverse effects on male rat reproductive organs, few studies have quantified alterations caused by its low doses. Quantification of these alterations, especially in the testis, was measured using morphometry. A single dose of cadmium chloride (1 or 1.2 mg/kg BW) was injected i.p. in adult rats, killed after 7 or 56 days. The lower dose caused slight alterations as measured by morphometrical analysis. The higher dose caused significant reduction in testis and epididymis weight, gonadossomatic index and length of seminiferous tubule (ST) after 7 and 56 days. Cadmium significantly reduced the ST diameter after 56 days. Decreased volume density of ST, after 7 and 56 days, was accompanied by an increase in interstitium volume density. The damage caused by the dose of 1.2 mg/kg can be clearly observed with light microscope. After 7 days, the tubule lumens were filled with degenerated germ cells and multinucleated spermatid aggregates. Vacuolization of the seminiferous epithelium was also observed. After 56 days, increased damage resulted in vacuolated ST, consisting only of Sertoli cells. Scanning electron microscopy examination of the testis showed that, in the group cadmium treated (1.2 mg/kg) and killed after 56 days, the interstitial tissue presents a compact and fibrous appearance with absence of fenestrae. The seminiferous epithelium height diminished and the absence of spermatozoa can be noted. The results show that a very small difference of Cd dose causes a sudden increase in testicular damage, apparently overpowering this tissue's natural defences.