Male and female mice (C57BL) were chronically exposed (life-long, 24 h/day) to mobile phone communication electromagnetic fields at approximately 1966 MHz (UMTS). Their development and fertility were monitored over four generations by investigating histological, physiological, reproductive and behavioral functions. The mean whole-body SARs, calculated for adult animals at the time of mating, were 0 (sham), 0.08, 0.4 and 1.3 W/kg. Power densities were kept constant for each group (0, 1.35, 6.8 and 22 W/m(2)), resulting in varying SARs due to the different numbers of adults and pups over the course of the experiment. The experiment was done in a blind fashion. The results show no harmful effects of exposure on the fertility and development of the animals. The number and the development of pups were not affected by exposure. Some data, albeit without a clear dose-response relationship, indicate effects of exposure on food consumption that is in accordance with some data published previously. In summary, the results of this study do not indicate harmful effects of long-term exposure of mice to UMTS over several generations.
In mammals, the duration of the cycle of the seminiferous epithelium (DCSE) largely differs between species, but is remarkably stable within a species, usually showing variations of 1%-3%. It is difficult to change the DCSE, e.g., by hormones or chemicals. Initial experiments, employing quantitative RT-PCR, aimed at investigating the diurnal profiles of the clock genes Arntl (previously called Bmal1) and Per1 in testes and kidneys of Djungarian hamsters (Phodopus sungorus). While the testicular levels of Arntl were almost constant, clear diurnal variations were identified for Per1. In order to clarify whether day length (T-cycle) is a factor for DSCE, adult male hamsters (n = 20 per group) were exposed to normal (T = 24 h), prolonged (T = 25 h), or shortened (T = 23 h) T-cycles, with cycles thus being longer or shorter by 4.2% compared to the normal condition. Exposure lasted for 43 days, during which the activity of the animals was recorded to confirm entrainment. DCSE was estimated by incorporation of bromodeoxyuridine in dividing cells and the immunohistochemical localization of labeled cells in stages I-XII of the seminiferous epithelium. Despite the low variability of the results and the close agreement with previously published data, no effects of prolonged or shortened T-cycles on DCSE could be identified (24 h: 7.98 ± 0.05 days; 23 h: 7.94 ± 0.04 days; 25 h: 7.91 ± 0.03 days; P > 0.05). The results strongly indicate that the high temporal precision of spermatogenesis is independent of the central circadian clock.
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