18 July 2010.

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Our previous experiments to study the effect of stress adaptation on pubertal development in carp showed that repeated temperature stress and prolonged feeding with cortisol-containing food pellets, which mimics the endocrine stress effects, retarded the first waves of spermatogenesis and decreased 11-ketotestosterone (11KT) plasma levels. The objective of the present study was to investigate whether the decrease in plasma 11KT is caused by a direct effect of cortisol on the steroid-producing capacity of the testis or by an indirect effect, such as a decrease in plasma LH. Pubertal and adolescent isogenic male common carp (Cyprinus carpio L.) were fed with either cortisol-containing food pellets or control food pellets over a prolonged period. Our results indicate that cortisol has a direct inhibitory effect on the testicular androgen secretion independent of the LH secretion. Furthermore, the pubertal period is critical to the influence of cortisol regarding testicular androgen secretion, because the effect is no longer observed at adolescence.

In order to better quantify the molecular mechanisms regulating final oocyte maturation and spawning, complete coding sequences with partially or fully untranslated regions for the steroidogenic enzymes, cytochrome P450 aromatase and 20b-hydroxysteroid dehydrogenase, were cloned from ovaries of Atlantic cod (Gadus morhua). The nucleotide and amino acid sequences showed high homologies with the corresponding sequences of other fish species, and conserved features important for functionality were identified in both predicted proteins. The sequences of the corresponding genomic loci were also determined, allowing the design of mRNA-specific quantitative PCR assays. As a reference gene for the real-time RT-PCR assays, eukaryotic elongation factor 1a was chosen, and the mRNA as well as the genomic sequence was determined. In addition, a real-time quantitative PCR assay for the 18S rRNA was adapted to be used in cod. Analysis of immature and maturing female cod from July to January respectively showed that the enzyme genes showed the expected quantitative changes associated with physiological regulation. However, mRNA for eukaryotic elongation factor 1a, and to a lesser extent even 18S rRNA, showed variable expression in these samples as well. To find accurate standards for real-time PCR in such a dynamic organ as the cod ovary is not an easy task, and several possible solutions are discussed.

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Study Type – Diagnostic (non‐consecutive)
Level of Evidence 3b OBJECTIVE To evaluate the safety and efficacy of a new semen analysis protocol after vasectomy, where clearance is given to patients who provide a single semen sample with <100 000 immotile sperm/mL at ≥3 months after vasectomy. PATIENTS AND METHODS Between 1 July 2005 and 31 March 2008, 1073 men provided a first semen sample at ≥3 months after vasectomy. Semen was first evaluated on a wet‐slide preparation. Those samples with no (‘azoospermia’) or sporadic immotile spermatozoa could be cleared without further analysis. Samples with motile sperm were immediately labelled as potentially fertile, while those with a significant number of immotile sperm were re‐analysed using a Neubauer haemocytometer. All samples with <100 000 immotile sperm/mL were cleared. RESULTS Of men providing semen at 3 months after vasectomy, 96% could be cleared. No sperm were seen (‘azoospermia’) in 51.3% of samples, and 44.7% of samples contained <100 000 immotile sperm. No paternity has been reported in the cleared group after a follow‐up of at least 1 year. CONCLUSIONS A protocol stipulating that patients can be cleared after a single semen sample containing <100 000 immotile sperm/mL at ≥3 months after vasectomy is safe and dramatically reduces the number of men who cannot be cleared at 3 months after vasectomy.