SUMMARY:The restriction of the mechanisms of cell proliferation in murine seminiferous epithelium, in terms of induction of programmed cell death until recently has not been fully analyzed. The aim of this work was to assess the effect of Malathion (MP) on testicular morphology and function in mouse spermatogenesis. For the experiments, male albino mice of strain NMRI-IVIC, weighing between 30-40 g were used, and divided into control and experimental groups of 5 each. The animals of the experimental groups were injected with a single dose of MP: 241mg/kg weight (1/12 LD 50 ) resuspended in 0.9% saline, intraperitoneally. Animals were sacrificed at 8.3, 16.6 and 33.2 days post-injection (first, second and third spermatogenic cycles). Testicular samples were obtained for light microscopy (LM), transmission electron microscopy procedures, and to detect apoptosis and p53 antigen by immunohistochemical methods. Blood was collected to quantify testosterone and plasmatic cholinesterase activity. From 8.3 days, Sertoli cell vacuolization, karyolisis of pachytene spermatocytes and Leydig cells and a decreased in average of the diameter of seminiferous tubules was observed. No damage to inter-Sertoli cells junctions was detected. Percentage of seminiferous tubules showing germ cells apoptosis was increased from 8.3 days, plasmatic acetylcholinesterase activity was reduced in the group treated only 24 hours after administration of MP. Serum testosterone levels were low in treated animals at 16. 6 and 33.2 days. p53 was mostly expressed in pachytene spermatocytes from 8d. The findings of this study indicate that MP alters the testicular function affecting the DNA and interfering with spermatogenesis as well as steroidogenesis.

Scorpion envenoming is a public health concern in northeastern Venezuela. Specimens of the genus Tityus are responsible for most of these. In experimental animals, Tityus venom produces histopathological changes in the skeletal muscle and pancreas, but its toxicity to the reproductive system has not been studied. The aim of this work is to describe the histopathological changes in testis and epididymis of albino mice induced by the administration of Tityus n. sp. venom. Sub-lethal doses of venom (3.75 mg/g mouse) were administered intramuscularly (IM) daily for 4 days. On the fifth day, the animals were sacrificed and the testes and epididymes were quickly removed and processed for light microscopy. The venom induced alterations in spermatogenesis. Sertoli cell vacuolation, immature germ cell shedding, spermatocyte arrest, and low sperm volume were observed in seminiferous tubules. Leydig cells were hardly affected. Vascular dilation and congestion were detected in the interstitial tissue. Immature germ cells were found in epididymal tubule lumina, but no abnormalities were observed in epididymal epithelial cells. These results show that Tityus n. sp. venom causes changes in mouse seminiferous epithelium, probably due to indirect action through the Sertoli cell