With the advancement in the embryo culture media, which supports nutrient requirements of embryos up to 5 to 6 days, there’s a chance to select more viable embryos, which are more likely to result in pregnancy, compared to earlier stages. Also, there is a controversy regarding the frozen embryo transfer compared to the fresh type. To compare the chemical pregnancy rates between fresh embryo transfer (ET), and frozen embryo transfer (FET), on day 3 (cleavage), and day 4 (morula) of development. In this retrospective study, data of 242 fresh and 758 frozen embryo transfer cycles were obtained in one infertility center in Isfahan, Iran. The study’s groups were assigned based on the day of fresh or frozen embryo transfer (day 3, or day 4 embryos) and the embryo grading. Chemical pregnancy was the main outcome measurement (implantation rates). The chemical pregnancy rate was higher in the good quality frozen embryo day 3 and transfer on day 4 group (40.1%). This rate was near the results of transferring the good quality frozen embryo on day 4 (39.2 %). There was no significant difference in the chemical pregnancy rate related to the number of transferred embryos (p = 0.55). The higher PRs, when the embryos were transferred on day 4, provided further support for the morula stage embryo transfer, possibly because of better synchrony with the endometrium. It is concluded that morula/compact embryos are good candidates for embryo transfer, which simultaneously reduces the number of transferred embryos.

Obesity, a global health issue, is associated with numerous diseases and has been shown to affect male reproductive health by inducing endocrine hormonal changes, chronic inflammation, oxidative stress and epigenetic alterations in reproductive cells. This study investigates the impact of obesity on testicular gene expression across mice, monkeys and humans, identifying 730 conserved testis-specific genes. High-fat diet-induced obesity upregulates GNG5, INHA, MSH5, SLC30A8 and SLC7A4 in testes, suggesting their potential as regulatory targets in testicular damage associated with obesity. Single-cell analysis reveals species-conserved expression patterns of SLC7A4 in Sertoli cells and SLC30A8 in SPG cells. It also confirmed that SLC30A8 and SLC7A4 were significantly upregulated in the testes of spontaneously obese mice. The findings highlight the potential of these genes as regulatory targets in obesity-related testicular dysfunction, providing insights into male reproductive health impairments caused by obesity.

Dry incubators prevent bacterial growth and allow time-lapse imaging. However, they cause more significant osmotic pressure changes in the culture medium than in humidified incubators. Few reports have explored the effect of osmotic pressure on human embryos cultured under different conditions. This study examined how changes in osmotic pressure affect human embryos in a dry incubator. The study incubated embryos in culture mediums covered with mineral oil of varying viscosities and quantities. The osmotic pressure of the culture medium was measured daily for six-day period (Day 0–6) in four experimental groups established by varying the viscosity and volume of mineral oil: low viscosity (Light), 3.0 ml or 4.5 ml, and high viscosity (Heavy), 3.0 ml or 4.5 ml of mineral oil. The Light 3.0 ml and Heavy 4.5 ml groups, showing the greatest difference in the osmotic pressure, were used to culture of human embryos. After six days of incubation, the osmotic pressure increased the most in Light 3.0 ml group. Heavy 4.5 ml group had the smallest change. However, no significant differences were noted in the formation rates of blastocysts, good-quality blastocysts, or cell count between the two groups. The study suggests that even when the culture medium is covered with heavy mineral oil in a dry incubator, osmotic pressure increases after six days but does not significantly affect the formation of blastocysts. These findings provide valuable insights into the effects of varying osmotic pressure on embryonic development and may help in optimizing conditions for in vitro fertilization.

Immunological castration can be an alternative to traditional surgical castration. The active immunization against GnRH or kisspeptin has a castrating effect. To date, the fusion protein vaccine of combination with GnRH and kisspeptin have not been studied. Thus, the present study will develop a GnRH6-kisspeptin vaccine by genetic engineering method and investigate its immunocastration effect in male rats. Twenty 20-day-old male rats were randomly divided into two groups: the control group (n=10) and the immunization group (n=10). The initial immunization took place at week 0 followed by three booster doses administered intervals. The control group received an equivalent dose of white oil adjuvant. Orbital blood samples were collected at various time points following the initial immunization, at 0, 2, 4, 6, 8, 10 and 12 weeks, respectively. The entire left testis was weighed and its volume measured at week 12. Samples from the right testis were obtained for histological analysis. Serum levels of GnRH and kisspeptin antibodies, as well as testosterone levels were determined using ELISA. The results showed that the serum levels of GnRH and kisspeptin antibody titres of the immunized rats were significantly higher compared to the control group (P<0.05). Additionally, the testosterone concentration was effectively reduced following the intensified immunization. The testes of the immunized group exhibited a reduction in size and a significant decrease in the number of spermatogonia in the testicular tissue compared to the control group (P<0.05). These data indicate that the recombinant GnRH6-kisspeptin protein effectively induced immunological castration in rats.

Zygote wishes to inform its readers that its Editor-in-Chief has decided to retract the above article after an investigation carried out in compliance with the Committee on Publication Ethics guidelines found that the authors duplicated substantial parts of the following two articles:

1. 1. Kim H, Yamanouchi K, Nishihara M. (2006) Expression of ski in the granulosa cells of atretic follicles in the rat ovary. J. Reprod. Dev. 52, 715–721

2. 2. Kim H, Yamanouchi K, Matsuwaki T, Nishihara M. (2012) Induction of Ski protein expression upon luteinization in rat granulosa cells without a change in its mRNA expression. J. Reprod. Dev. 58, 254–259

Sloan-Kettering virus gene, a product of a cellular proto-oncogene c-Ski is a unique nuclear pro-oncoprotein and belongs to the Ski/Sno proto-oncogene family. The aim of the present study was to locate Ski protein in rat ovaries in order to find insights into the possible involvement of Ski in follicular development. First, expression of c-Ski mRNA in the ovaries of adult female rats was confirmed by RT-PCR. Then, ovaries obtained on the day of estrus were subjected to immunohistochemical analysis for Ski and proliferating cell nuclear antigen (PCNA) in combination with terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL). RT-PCR and in situ hybridization revealed that c-Ski mRNA was expressed in the ovaries of the adult rat on the day of estrous and localized mainly in the granulose cells. Ski was expressed in granulosa cells that were positive for TUNEL, but negative for PCNA, regardless of the shape and size of follicles. Expression of Ski in TUNEL-positive granulosa cells, but not in PCNA-positive granulosa cells, was also verified in rats having atretic follicles with double staining. These results indicate that Ski is profoundly expressed in the granulosa cells of atretic follicles, but not in growing follicles. Based on the present findings, Ski may play a role in the apoptosis of granulosa cells during follicular atresia.