Fresh and frozen epididymal sperm yield comparable pregnancy rates for intracytoplasmic sperm injection

The Influence of Cryopreservation on Sperm Morphology and Its Implications in Terms of Fractions of Higher-Quality Sperm

Background/Objectives: Male infertility is a significant global health issue, comprising approx. 50% of all infertility cases. Semen cryopreservation, a critical component of assisted reproductive technologies (ARTs), is a method commonly used in a wide range of situations, including gonadotoxic treatments such as radiation or chemotherapy, hazardous occupational exposures, and various medical conditions. Although historically viewed as potentially damaging to sperm, recent findings suggest that cryopreservation, when performed with appropriate techniques, may in fact enhance semen quality by improving the proportion of healthy spermatozoa, particularly in terms of their morphological parameters. The aim of this study was to evaluate the impact of cryopreservation on sperm morphology and viability, utilizing advanced morphological assessments pre- and post-freezing. Methods: Semen samples were collected from 97 patients undergoing infertility treatment at the KRIOBANK clinic (Białystok, Poland). The semen was liquefied and prepared in the form of slides. Sperm morphology was then assessed using an OLYMPUS BX40 microscope at 60× magnification. Results: The findings of the study revealed significant improvements in sperm morphology, with increased percentages of normal sperm and reductions in deformation indices post-thaw. Conclusions: The findings indicate that optimized cryopreservation protocols may support the selection of higher-quality sperm, offering valuable benefits for ART applications. These results challenge certain past assumptions regarding the impact of cryopreservation and underscore the need for refined freezing techniques to maintain and potentially enhance semen quality for reproductive use.

Establishment of a pregnancy following intravaginal insemination with epididymal semen from a dog castrated due to benign prostatic hyperplasia

Benign prostatic hyperplasia was diagnosed in an American Staffordshire Terrier of high breeding value presenting concurrent haematuria. Castration as a treatment was synchronized with the oestrus cycle of a bitch selected for insemination. After castration the cauda epididymis was flushed with Gent semen extender and collected spermatozoa were filtered and analysed by Hamilton Thorn computer assisted sperm analysis. A total of 7 ml semen containing 742 x 10(6) spermatozoa with 76.5% mean motility was used for insemination. Intravaginal insemination of the bitch was performed with an insemination catheter for dogs (Kruuse, Marslev, Denmark) on the day when plasma progesterone levels reached 9.9 ng/ml. Normal pregnancy without complications resulted in eight live-born puppies 63 days after insemination. This is the first report of a normal pregnancy and birth of puppies from a bitch inseminated with epididymal semen obtained from a dog affected by benign prostate hyperplasia.

Intracytoplasmic injection of frozen-thawed epididymal spermatozoa in a nonhuman primate model, the cynomolgus monkey (Macaca fascicularis)

Intracytoplasmic sperm injection (ICSI) with frozen-thawed epididymal spermatozoa was performed in the cynomolgus monkey (Macacafascicularis) to produce embryos in vitro. Eleven sexually mature females were hyperstimulated with an GnRH agonist (1.8 mg active triptorelin per 2 kg body weight), followed (2 weeks later) by rFSH (37.5 IU per 2 kg daily) for 12 days, and finally 1000 IU of hCG. Epididymal spermatozoa were collected from a single adult male monkey. The first stimulation cycle resulted in 90 oocytes; 70% of which were metaphase II (MII). Sixty-four percent of these MII oocytes were fertilized. Comparing ovarian response of five monkeys that underwent a second stimulation cycle there was an increase in oocyte quantity (13.2 versus 9.2 oocytes per monkey) but the percentage of MII oocytes remained the same at 58%. Fertilization and cleavage rates were also reduced but there was an increase in the number of embryos available for transfer. Overall, four monkeys became pregnant resulting in the birth of two healthy infants and two abortions. These findings show that ovarian stimulation by GnRH-rFSH did not compromise the developmental competence of the oocytes; effective combination of cryopreservation of epididymal spermatozoa and ICSI is possible in nonhuman primate reproduction, and thus has potential application in the conservation of highly endangered nonhuman primate species, and the cynomolgus monkey is a reliable biomedical research model to study the potential risks and benefits associated with assisted reproductive techniques prior to approval for clinical trials on humans.

The outcome of intracytoplasmic injection of fresh and cryopreserved ejaculated spermatozoa--a prospective randomized study

BACKGROUND

The overall aim of this prospective, randomized study was to compare the reproductive potential of fresh and frozen-thawed ejaculated spermatozoa from oligoasthenoteratozoospermic patients in an intracytoplasmic sperm injection (ICSI) procedure.

METHODS

All patients consenting to participate in this study had a sperm sample frozen prior to the start of a cycle. Patients were randomized using a random number table to undergo ICSI with either fresh (group A, n = 118) or frozen-thawed (group B, n = 122) spermatozoa. All prognostic variables were equally distributed among the two groups.

RESULTS

The pregnancy rate per started cycle was 29.7% in group A and 38.5% in group B, P > 0.05. A significant difference was observed in the rate of ongoing pregnancies between group A (23.7%) and group B (35.2%), P < 0.05.

CONCLUSION

From our data we can conclude that cryopreservation of spermatozoa from men with poor sperm quality does not negatively affect fertilization and pregnancy rates after ICSI. A larger study will be needed to investigate whether the use of cryopreserved spermatozoa can be helpful in selecting the most vital spermatozoa for ICSI.

Cryopreservation of epididymal dog sperm

A method of cryopreservation was developed for sperm salvaged from the cauda epididymis and vas deferens of domestic dog testes. Four modifications of the glycerol concentration of a buffer used for cryopreservation of dog ejaculates and two freezing rates were assessed for their effect upon post-thaw spermatozoal motility and morphology. There was no statistical difference between the four glycerol concentrations or the two freezing rates and the buffer containing 6% glycerol and the freezing rate provided by 0.5 ml straws was chosen for further study. This method resulted in a significant reduction in the percentage of live spermatozoa detected with Hoechst staining and a reduction in the percentage of capacitated spermatozoa after freeze-thawing. However, there was no difference in the ability of frozen-thawed spermatozoa to penetrate homologous oocytes. This study demonstrates that cryopreservation of epididymal canine sperm can be performed using methods similar to those established for ejaculates of the same species, and that despite some damage, spermatozoa retain their functional ability.

Fundamental aspects of sperm cryobiology: the importance of species and individual differences

While semen cryopreservation is successfully used for a few species, application to other species can be problematic. Here, I argue that species differences in female tract anatomy, subtle differences in sperm transport mechanisms, ability to time inseminations and deliver spermatozoa effectively are powerful determinants of fertility with cryopreserved spermatozoa. Poor sperm survival represents one major aspects of the problem and determining biophysical characteristics of the sperm plasma membrane is an established approach to solving it. However, this approach is unable to account for the consistent differences in post-cryopreservation sperm quality between individual males, an effect that is recognized is many species although only documented in a few. Searching for genetic differences between these individuals might offer a genomically-based direction in semen cryopreservation research. Cryopreservation of spermatozoa and spermatogenic cells for intracytoplasmic sperm injection has been developed primarily to deliver an intact genome and presents a very different set of technical problems.