Branko Radaković

Comparison of protective media and freezing techniques for cryopreservation of human semen

OBJECTIVE To evaluate the influence of cryopreservation medium and freezing-thawing techniques on human sperm motility and morphology. STUDY DESIGN 63 semen samples were obtained from 39 donors to the artificial insemination programme. Possible effects of the sperm dilution with cryomedium on the motility were examined 10 min after exposure of 24 high initial quality semen samples to TEST-yolk ¿zwitterion-citrate-egg yolk extender containing TES [N-Tris (hydroxymethyl) methylaminoethane sulfonic acid] and Tris [(hydroxymethyl) aminomethane]¿ and human sperm preservation medium (HSPM). Post-thaw sperm motility from 24 frozen semen samples was examined comparing the cryoprotective efficacy of TEST-yolk and HSPM following different freezing techniques (vapour freezing, fast programmable freezing and slow programmable freezing). The relationship of sperm morphology to the effects of freezing was investigated on 39 semen samples following different freezing techniques. Post-thaw sperm motility from 39 frozen semen samples was compared among three groups divided according to the percentage of morphologically normal cells (<40, 40-50 and >50%) in fresh semen. RESULTS Exposure of spermatozoa to cryomedia for 10 min at room temperature significantly reduced motility in TEST-yolk treatment group for 9% and in HSPM treatment group for 18% (P<0.01). The recovery of motile sperms (mean+/-standard deviation) was 49+/-15.7, 43+/-15.2 and 52+/-16.8% when TEST-yolk was used and 34+/-17.8, 32+/-18.2 and 50+/-13.6% when HSPM was used as a cryopreservative following vapour freezing, and fast and slow programmable freezing, respectively. Following vapour freezing and also following fast programmable freezing, the recovery of motile sperm was significantly higher (P<0.05) after addition of TEST-yolk medium than after addition of HSPM. Post-thaw motility of the sperm cryopreserved in HSPM showed significant differences (P<0.05) after three different freezing techniques. The recovery of motile sperms was 57+/-26.4, 38+/-8.6 and 38+/-17.3% in groups with >50, 40-50 and <40% morphologically normal cells, respectively. The percentage of morphologically normal spermatozoa was reduced 8% after vapour freezing and 6 and 3% after fast and slow programmable freezing, respectively. The results were statistically analysed using SAS/STAT software. CONCLUSIONS Slow programmable freezing was superior to vapour freezing and fast programmable freezing as a method for sperm cryopreservation. However, none of these methods of freezing had discernible effects on sperm morphology. Motility of spermatozoa decreased due to the exposure of semen to cryomedium. TEST-yolk was a superior cryomedium to HSPM. Fresh semen with more than 50% of morphologically normal cells showed the best recovery of motile cells after freezing and thawing.

Preovulatory progesterone rise during ovarian stimulation for IVF

Abstract The aim of this review is to analyze the relationship between the preovulatory progesterone (P) rise and the in vitro fertilization (IVF) pregnancy outcome. It also investigates the sources and effects of P level increase, including the underlying mechanisms and potential strategies in preventing its elevation during ovarian stimulation. The origin of production of P in the early follicular phase is adrenal which shifts toward the ovaries prior to the ovulation. Several factors contribute to the etiology of P level increase including the number of multiple follicles, the overdose of gonadotropins and poor ovarian response. Nowadays, the influence of the preovulatory P rise on IVF outcome remains controversial. Several authors have failed to demonstrate any negative impact, while others reported a detrimental effect associated with the rise of P. It seems that P rise (≤1.5 ng/ml or 4.77 nmol/l) may have deleterious effects on endometrial receptivity, namely, accelerating the endometrial maturation process that subsequently narrows the time-frame for implantation and thus decreases pregnancy rates. To prevent a P rise, it might be preferable to use milder stimulation protocols, earlier trigger of ovulation, cryopreservation of all embryos and transfer in the natural cycle.