The mycotoxin T-2 has many harmful effects on mammalian cells and reproductive functions. In the present study, the in vitro effect of T-2 toxin on mouse blastocysts was examined. Embryos were cultured in media supplemented with 0.5, 0.75 and 1 ng/ml T-2. Different exposure times were applied [96 h (treatment I) or 24 h following 72 h in toxin-free media (treatment II)]. Blastomere number, nuclear chromatin status and blastocoel formation were investigated in blastocysts. Our data show that the effect of T-2 toxin may vary depending on the stage of the embryo at the start of exposure. At 96 h of exposure, the blastocysts had blastomeres with normal chromatin quality but their developmental potential was decreased. After 24 h of exposure applied following a 72-h culture, blastomeres had a higher level of chromatin damage, although their developmental potential was the same as in the control embryos. In both cases, decreased mitotic rate was found, which resulted in decreased blastomere number even at low toxin concentration.

The aim of the present study was to compare the survival and developmental rate of canine isolated preantral follicles (PAFs) after cryopreservation with different methods (closed vs open vitrification). Follicles were isolated from ovaries randomly divided into three groups: fresh control, OPS (open pulled straw) vitrified and cryotube (CT) vitrified. Post-thaw viability of follicles and oocytes was assessed. Fresh and vitrified/thawed PAFs were cultured in 20 µl drops of FSH-supplemented medium for 10 days. Follicular growth, survival rate, estradiol production and ovulation rate were examined. CT method resulted in lower rate of live cells (58.7%) and oocytes (38.8%) than that of fresh ones (83.6% and 64%, respectively) and OPS (80.3% and 79.3%, respectively). Survival rate was similar to fresh follicles in OPS group (98.5% and 95.4%, respectively), while CT decreased the survival to 81.2%. Fresh follicles showed continuous growth, while CT follicles stopped to increase their size after 2 day. In the OPS vitrified follicles, this halting occurred between Day5 and Day10. Fresh follicles showed the highest estradiol production (range: 26.9 - 266.2 pg/ml). Comparing the two vitrified groups, lower estradiol concentration range was measured in the CT group (7.8-48.7 pg/ml vs. 15.4-89.6 pg/ml). Ovulation rate in each group was lowest in the OPS group (1.7% vs 7% and 8.9% in fesh and CT, respectively). Our data show that OPS vitrification provides superior survival rate, in vitro growth and hormonal production to CT. To our knowledge, these are the first results on comparing different cryopreservation protocols on canine isolated preantral follicles.

The aim of this study is to obtain a more complete picture of blood plasma melatonin concentrations in the donkey mares. To this purpose, sampling and statistical processing were carried out in such a way that allowed the researchers to establish the annual and daily rhythms. Based on human observations, according to the hypothesis of the authors, the blood plasma melatonin concentration of pregnant individuals rises during the late gestational period, before parturition. To confirm this, the melatonin concentrations of pregnant and non-pregnant jennies were monitored and compared. In regard to the circannual rhythm, the significantly lowest midnight melatonin value (27.67 pg mL^–1) was typical for the summer solstice. Under consideration of circadian changes, a significantly strongest melatonin production (45.16 pg mL^–1) was observed on the night of the winter solstice (p < 0.001). Considering gestational age, the blood plasma melatonin concentration (around 38 pg mL^–1) does not change as gestation progresses (p = 0.136). The results obtained in this studied population of the domestic ass usefully expand the little knowledge previously gathered about the development of the blood plasma melatonin concentrations of this species.

In the field of reproductive science, there is an increased interest in the application of ovarian preantral follicles. Since the ovary contains a great amount of preantral follicles (PAF), the cryopreservation and in vitro culture of such follicles support the fertility preservation of domestic animals with high genetic value, endangered or zoo animals, and women before anticancer therapy. To date, no standard freezing or vitrification protocol is available in human or animals. The aim of the present study was to examine the viability of preantral follicles cryopreserved using freezing or vitrification protocols: cryotube freezing or OPS vitrification.

The objective of this study was to analyse the effect of slow freezing on the morphology and viability of canine isolated preantral follicles. Ovaries were collected from ovariohysterectomy bitches being in different ages. Preantral follicles were isolated from ovarian cortex using collagenase-based digestive solution and randomly divided into two groups: fresh control and slow frozen. Fresh and frozen/thawed preantral follicles were cultured individually in 100 µl drops of culture medium for 10 days at 38.5 °C with 6.5 % CO₂, and half of the medium was changed and samples from culture media were collected on Day 2, Day 5 and Day 10 for hormonal analysis. Post-thaw live cell rate, normal morphology rate, area change, and estradiol and progesterone production were examined. Frozen/thawed follicles have lower number of live cells than that of fresh ones (94.69 % ( ± 6.97) vs 98.58 % (± 1.71), respectively [p < 0.05]). Normal morphology rate was different only on Day2 (91.2 % in fresh and 50 % in frozen/thawed, p < 0.05) and showed decreasing tendency in both groups. Differences in follicular growth were found on Day5 and 10, when fresh follicles showed lower area than that of frozen/thawed ones (5.84 vs12.62 mm² [p < 0.005] and 6.47 vs 10.75 mm² [p < 0.05], respectively). Regarding the hormonal production, estradiol and progesterone concentrations were lower in frozen/thawed samples than that of fresh follicles throughout the culture period. In conclusion, our data suggest that slow freezing can provide canine follicular survival, however, the quality and viability of the follicles are reduced.