"The effect of the administration of mepivacaine hydrochloride on the histological and electronmicroscopical appearance of the rat testis "

Abstract

) Int his investigation the histology and histochemistry of the testes of albino rats receiving Mepivacaine-HCL solution of different doses and concentrations were studied using both light and electron microscopes. The testes of treated animals showed different degrees of damage. The severity of the damage was classified into "slightly", "partially" and "severely" damaged tubules. Vacuolation was seen in the "slightly" damaged tubules by many investigators who gave different explanations about how and what causes vacuole formation. In this study, a new hypothesis was introduced. The late spermatids were readily damaged after Mepivacaine-HCl administration. Then, the carly spermatids showed different degrees of damage and degeneration; the mitochondria appeared extremely electron dense and scattered in the cytoplasm instead of being close to the cell membranes. The primary spermatocytes were the next in order of sensitivity. A marked morphological alongation of the cytoplasm of these cells was usually seen. Their mitochondria showed a distant swelling and cup-shaped mitochondria were also found. These were not typical of germinal cells of control testes. The secondary spermatocytes showed marked destruction in some parts of the cytoplasm and the nuclear membrane appeared bulging into the cytoplasm. Their mitochondria showed disruption and fusion of the membranes. The light microscope did not determine the extent of damage of spermatogonia. However, the electron microscope showed slight changes of the Golgi apparatus and mitochondria after administration of Mepivacaine-HCl. The mitochondria of spermatogonia were frequently swollen and their cristae were disintegrating and coalesoing together forming a condensed electron dense bodies. Sertoli cells were the cell type most resistant to drug administration. The boundary tissue of tubules, "partially" and "severely" damaged, showed a marked increase in thickness at the light microscope level. At the electron microscope level, the boundary tissue could be resolved into the four layers which became highly folded. Many extremely large lipid droplets were present in the seminiferous epithelium of the treated animals as well as in the interstitial cells. Sinoe Mepivacaine-HCl has a vasoconstructor effect and spermatogenesis is very sensitive to reduced blood flow, it could be concluded that the injurious effect of the administration of Mepivacaine-HCl intraperitoneally is probably due to reduced blood flow to the testes.