Poster
# 44
Poster |
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6th Internet World Congress for Biomedical Sciences |
Robert Toman(1), Peter Massanyi(2), Norbert Lukac(3)
(1)(2)(3)Slovak Agricultural University - Nitra. Slovakia
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[Toxicology] |
[Pathology] |
[Reproduction Sciences] |
Cadmium was revealed as a toxic element for a reproductive system in many experimental works using the histological methods of investigation (1,2,3,4,10). It causes the severe damage of capillary system of the testis and then the spermatogenesis is ceased. It is known that after intraperitoneal application of cadmium chloride the testes undergo rapid necrosis. The gonads are more rapidly damaged after the intravenous application of cadmium. Cadmium is in that case directly carried to the target organs.
The testis failure rises also after the oral administration, as we have described in our previous experiments on rabbit (10). The destruction of the testes depends on the dose used in the experiment or the duration of the experiment. Cadmium is cumulative element and when the harmful level of this metal is reached in organism, or in concrete organ, i.e. testis, it works toxic. Cadmium causes also changes in the female sexual organs (4-8). To reveal some characteristic signs of cadmium effects on the testis we aimed at the scanning electron microscope technique.
The mature laboratory rats of 400 - 440 grams of body weight were used throughout the experiment. Ten control and ten experimental animals were kept in the same conditions. Cadmium (CdCl2, Sigma, St. Louis, MO, USA) was applied in the single intraperitoneal dose of 0,04 mmol.kg-1 of body weight. After 24 hours, the animals were killed and the samples of the testes were processed for submicroscopic examination. Tissue excisions from the testes were washed with 2 % glutaraldehyde in Sörensen´s buffer. The excisions were fixed with 4 % glutaraldehyde in Sörensen´s buffer for 4 hours. When the samples were washed and dehydrated, then they were dried by the critical point dry method and gold covered. The prepared samples of testis were examined under the Tesla BS-601 scanning electron microscope.
Oedema and red coloring of the testes after 24 hours characterized the macroscopic findings. The electron microscopic examination revealed the injured blood vessels fig. 2 with diapedesis. The normal capillary of control rat shows fig. 1. As a vessel result of this damage we described the severe damage of the germinal epithelium fig. 3 fig. 5, when compare with normal seminiferous tubule fig. 4. The degeneration of the epithelium proceeded form the margin of the tubule to the center. Under the lamina propria, there were observed places without any germinal cells fig. 7. It means, they lost their contact with lamina propria of the tubules. These cells appeared in the lumen of the tubules together with sperm cells undergoing the cytolysis.
The intertubular space was increased in volume after the cadmium application fig. 7. The interstitial tissue was extended due to the increase of the collagen fibers. The interstitial tissue, which forms the lower part of the testis volume in normal health rat, is shown on fig. 6.
Similar changes as described in this experiment we found also after the intratesticular injection of cadmium in rats (9). The changes were the same, total destruction of spermatogenesis. Also other authors found similar changes in the testes of various mammalian species (1,3,10,11). Gunn and Gould (2) noted that only 1/60 of subcutaneous dose is sufficient to produce testicular necrosis when applied directly into the testis. The testis failure caused by cadmium results form the ceased blood supply to the gonad (2). We found in our experiment damaged blood capillary in the testis. The blood elements passed through the damaged capillary wall into the surround space. The ischemic changes are the primary consequences of the cadmium effect in the testis. These changes lead to the testis oedema. The blood vessel injury was described also in other histological studies using the light microscopic techniques (1,3,10).
The scanning electron microscopic study of Vrzgulová et. al (11) aimed at effects of copper on the ram testes revealed the similar changes like releasing of germinal cells of lower developmental stages into the tubular lumen. In our study was found the same picture. It means, that spermatogonia and also primary spermatocytes are the most sensitive cell stages of spermatogenesis to the toxic elements. It leads to total infertility of affected animals. In our previous study we found the signs of recovering of the seminiferous epithelium 35 weeks after single intraperitoneal administration of cadmium (3).
Previously described (3,9,10) increase of the interstitial space was well observed also in our study. In normal testes the interstitial tissue is narrow and the seminiferous tubules form about 80 % of the testes volume (3). When cadmium is administered, the tubules will shrink. On the contrary, the interstitial tissue extends. The collagen fibers increase in number and by suggestions of Vrzgulová et. al (11) also the hyperplazia of the interstitial cells in rams after copper intoxication.
Cadmium applied to rats intraperitoneally caused haemorrhagic necrosis of the testes 24 hour after administration of metal. The spermatogenesis was ceased due to the damage of the blood vessels in the testis. The germinal cells evacuated from the lamina propria first and underwent the cytolysis. The another significant sign of the harmed testis by cadmium was the extension of the interstitial tissue. The changes found and described using the scanning electron microscopy are comparable with the another microscopic techniques and complete the knowledge about cadmium effects on the testis.
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[Toxicology] |
[Pathology] |
[Reproduction Sciences] |
