SPI and TDI Alterations of Seminiferous tubules in Adult Male Rats under Two Different Temperatures Induced Heat Stress

Objectives: Male infertility is to the inability of a male to in-duce pregnancy in a fertile female.Male factor is responsible for 30-50% of cases of infertility and about 20% of infertile men totally lack spermatozoa in their ejaculation.The testis of most animals, including human, rat, mouse, are found in the scrotum outside the main body cavity and are thus 2-8.c below the core body tempreture .Scrotal hyperthermia has been known as a cause of male infer-tility. Testicular heat stress even for a single short period can induce destruction in testicular tissue and spermatogenesis dis-turbances.In daily life, a various of external and internal factors could narrow this temperature difference, thus increasing the risk of abnormal spermatogenesis.Elevated scrotal tempreture causes testicular germinal atrophy and spermatogenic arrest among the germ cells. The types that are most vulnerable to heat are the pachytene and diplotene spermatocytes and the early round spermatids.Materials and Methods: Twenty-one adult male rats (4 months of age, 180-220g body weight) were purchased from animal house of faculty of science Urmia University. All ani-mals were kept under controlled environmental conditions at room temperature(22±2°C) with humidity of 50± 10% and a 12/12hr photoperiod. The animals were provided with standard diet pellets and water ad libitum.Animals were randomly categorized into 3 groups; group 1 served as a control, groups 2 and 3 were heat-stressed (39 and 43° for 20 min per day, respectively).The HS was induced through immersion of experimental rat scrotums in a water bath. After 35 days, the testicles were harvested, then dehydrated, cleand in xylene and embedded in paraffin wax. Thin sections (6μm in thickness) were cute and staind with hematoxyline and eosin for histopathological analysis. Then SPI and TDI altera-tions of Seminiferous tubules were analyzed in all experimental groups.Results: In HS-exposed groups, SPI and TDI Alterations of Seminiferous tubules showed significant decrease in a tempera-ture-dependent manner compared to the control group.Conclusions: These finding indicate that heat stress causes sig-nificant drop in TDI and SPI ratio.