Continuous measurement of secondary neutrons from cosmic radiation at mountain altitudes and close to the North Pole--a discussion in terms of H*(10).

Two Bonner sphere spectrometers (BSSs) have recently been installed to measure secondary neutrons from cosmic radiation continuously, one at the environmental research station 'Schneefernerhaus' at an altitude of 2650 m in Germany and the other at the Koldewey station close to the North Pole in Ny-Alesund, Spitsbergen. After unfolding, both systems provide neutron fluence energy distributions as a function of time. Based on these distributions and on fluence-to-dose conversion coefficients, mean ambient dose equivalent rate values of 75.0 +/- 2.9 nSv h(-1) and 8.7 +/- 0.6 nSv h(-1) were obtained for October 2008, respectively (quoted uncertainties represent standard deviations of 124 values obtained during the measurement period). Ambient dose equivalent rates measured by means of an extended rem counter at the Schneefernerhaus agree with those based on the BSS neutron energy distributions within 5 %. The ambient dose equivalent rate was also calculated based on simulated FLUKA neutron energy distributions in the atmosphere. Even without detailed modelling of the local environment, an agreement better than 30 % was obtained between the ambient dose equivalent rate based on the FLUKA distributions and those based on the BSS measurements at the Schneefernerhaus, for neutrons above about 20 MeV. This agreement is expected to be even better if the influence of the local environment on the measured neutron fluence energy distribution will be calculated.

The differential fate of mesonephric tubular-derived efferent ductules in estrogen receptor-alpha knockout versus wild-type female mice.

We investigated mesonephric tubular-derived efferent ductules in female wild-type (WT) and estrogen receptor-alpha knockout (ERalphaKO) mice from late fetal to adult life. On gestational day 17, efferent ductules in both fetal WT and ERalphaKO females were well developed and morphologically similar, although one third the size of the male counterpart. Unexpectedly, efferent ductules with a ciliated epithelium were still present on postnatal day 10 in WT and ERalphaKO females. By day 23, however, marked phenotypic differences occurred in efferent ductules of WT and ERbetaKO vs. ERalphaKO female mice. In the latter, efferent ductules became hypertrophied and dilated, whereas only small tubules remained in WT and ERbetaKO adult mice. The serum testosterone concentrations were similar in 21- to 25-day-old ERalphaKO, heterozygous, and WT female mice, suggesting that increased testosterone was not inducing enlargement of efferent ductules in ERalphaKO females. In conclusion, remnants of efferent ductules persisted in normal adult female mice, although these structures were greatly reduced in size compared with efferent ductules in ERalphaKO female mice. The underlying mechanism inducing hypertrophy and dilation of efferent ductules in ERalphaKO females is not clear, but secretory and/or reabsorptive function of female efferent ductules may involve ERalpha.

Gonadotropin induction of ovulation and corpus luteum formation in young estrogen receptor-alpha knockout mice.

Estrogen receptor-alpha (ERalpha) knockout (ERalphaKO) female mice are infertile. Initially, they exhibit normal follicular development, but by 4-5 wk of age, they begin to develop hemorrhagic ovarian cysts. Follicles in adult ERalphaKO female mice progress to the graafian stage, but there are no corpora lutea (CL). To test whether ERalpha is required for ovarian folliculogenesis, ovulation, and CL formation, eCG and hCG were used to ovulate 3- to 5-wk-old ERalphaKO and wild-type (WT) sibling mice. Gonadotropin administration resulted in ovulation in both ERalphaKO and WT mice. Gonadotropin-treated ERalphaKO females that ovulated produced 7.09 +/- 0.77 oocytes per mouse, whereas gonadotropin-treated WT female mice had 16.17 +/- 0.84 oocytes. Surprisingly, ruptured ERalphaKO ovarian follicles developed into CL that had normal morphology. Gonadotropin-treated ERalphaKO mice had 3-fold higher concentrations of serum progesterone than did control ERalphaKO mice that had been administered saline rather than gonadotropins. Thus, the CL in gonadotropin-treated ERalphaKO mice appeared to be steroidogenically functional. On the basis of these findings, ovarian folliculogenesis, ovulation, and CL formation can occur in the absence of ERalpha, although to a lesser extent than in WT mice.