Incidence of spontaneous ovulation and development of the corpus luteum in non-mated dromedary camels (Camelus dromedarius)

Effect of the interval from GnRH administration after ovarian super-stimulation on the recovered oocytes, and effect of the transferred cloned blastocysts on the pregnancy rate and pregnancy loss in dromedary camel

The present study was conducted to evaluate the number and maturity of the recovered oocytes after two intervals of in-vivo maturation. In addition to evaluating the effect of the developmental stage, as well as the number of cloned transferred blastocysts on the pregnancy rate and early pregnancy loss (EPL) in dromedary camel. The donor animals (n = 52) were super-stimulated using a single injection of 3000 IU of eCG followed by GnRH administration for oocyte maturation. Cumulus oocyte complexes (COCs) were collected by transvaginal ultrasound-guided aspiration (OPU) either 24-26 h or 18-20 h after GnRH administration. A fewer number of COCs with a lower percentage of oocyte maturity was observed at 24-26 h in comparison to 18-20 h. The effect of the cloned blastocysts' transferred number and developmental stage on the pregnancy rate and EPL was investigated. The total pregnancy rates at 10 days post-ET, 1 and 2 months were 21.9, 12.4, and 8.6%, respectively. Transfer of two or 3-4 embryos per surrogate was accompanied with a higher pregnancy rate at 1 and 2 months than a single embryo transfer. Rates of EPL were 43.5 and 60.1% at 1 and 2 months of pregnancy, respectively. The transfer of two embryos per surrogate was associated with a lower rate of EPL than ET of a single embryo at 1 and 2 months of pregnancy. Also, the ET of 3-4 embryos per surrogate showed a higher rate of EPL than the ET of two embryos at 2 months of pregnancy. ET of hatching (HG) blastocysts showed higher pregnancy rates and fewer EPL than ET of unhatched (UH) or fully hatched (HD) cloned blastocysts at 1 and 2 months of pregnancy. In conclusion, a high number of in-vivo matured oocytes can be recovered by ultrasound-guided transvaginal OPU from super-stimulated females using 3000 IU eCG and an interval of 18-20 h after GnRH administration. The transfer of two hatching cloned blastocytes per surrogate increases the pregnancy rate and decreases EPL in dromedary camels.

Effect of advancing the breeding season on reproductive performance of dromedary camels

This study examines the effect of advancing the breeding season on the reproductive performance of dromedary camels under an intensive management system. Using a synchronization protocol, timed natural mating in female camels was carried out either in September (2 months ahead of the natural breeding season, n = 182) or December (peak breeding season, n = 115). The ovarian responses (size of the dominant follicle at the time of mating and ovulation), pregnancy rate, and pregnancy losses were evaluated using ultrasonography. Blood samples were collected after mating to assess progesterone concentrations by RIA. The libido of male camels (n = 13) was evaluated objectively. Results showed that the percentage of female camels with an optimal sized follicle (11-17 mm) for breeding at the time of mating was lower in September compared to December (81.9 vs 91.3%, P = 0.03). The libido of male camels was lower in September than in December (P <0.001). The ovulation rate (86.3 vs 93.9%, P = 0.04), size of the ovulated follicle (12.7 ± 0.1 vs 13.7 ± 0.2 mm, P <0.001), pregnancy rates on Day 14 (47.8 vs 72.2%, P <0.001) and Day 90 (38.5 vs 60.9%, P <0.001) after mating was lower in September compared to December. However, pregnancy loss was not affected between months (15.7 vs 19.5%, P = 0.3). Among pregnant camels, the progesterone concentrations on Days 6, 8, 10, 12 and 14 after mating were lower in September as compared to December (P <0.001). In non-pregnant camels, the progesterone concentrations on Days 6, 8 and 10 after mating were also lower in September as compared to December (P <0.001). In conclusion, advancing the breeding season by two months, significantly affects the reproductive performance of dromedary camels, yet, acceptable pregnancy rates can be achieved.

Regression of corpus luteum in cetaceans: A systematic review

Functional and structural change of corpus luteum through the cascade of several genes in the ovary leads to ovulation and pregnancy. In most mammals, the absence of pregnancy leads to the disintegration of the corpus luteum. In the ovary of cetaceans, the regression of the corpus luteum gets delayed and persists on the surface as scars (corpus albicans). The database on luteolysis of mammals was collected and examined to know the mechanisms involved in the corpus luteum regression of cetaceans. Surprisingly, there existed no data on the concerned topic. Some past findings reported the persistence of ovarian scars through the entire life span, while few reported the regression. Also, those investigations were about the physiology and histology of corpus luteum regression. The pathways and the genes involved in the regression of the cetacean corpus luteum remain unexplored. This review is all about the regression of corpus luteum and recommends gene-based evolutionary studies in the future to resolve the existing theories on ovarian scar persistence in cetaceans.

Estradiol-17β Injection Induces Ovulation in Llamas

This study aimed to investigate the effect of three different doses of estradiol-17β on ovulation and subsequent luteal development and function in llamas. Twenty-three llamas were examined daily by transrectal ultrasonography until the detection of an ovulatory follicle (≥8 mm). Thereafter, animals were divided into five groups: Control (n = 3; treated with 1.6 ml of saline solution), GnRH group (n = 6, treated with an intravenous injection of 8.4 μg Buserelin), and estradiol groups that received 0.6 mg (E1, n = 4), 1 mg (E2, n = 4), or 1.6 mg (E3, n = 6) of estradiol-17β intravenously. Detection of ovulation was based on ultrasonographic visualization of disappearance of the largest follicle and subsequent presence of a newly formed corpus luteum (CL) and progesterone concentration exceeding 1 ng ml⁻¹. Daily blood samples were collected to determine plasma progesterone concentration. Ovulation rate was 0% for control and E1 groups, 25% for E2 group, and 100% for GnRH and E3 groups. Differences in the mean CL diameter between GnRH and E3 groups were not statistically significant. Plasma progesterone concentration was similar between groups during the different days in ovulated animals. However, the day that the plasma progesterone concentration was above 1 ng ml⁻¹ and the day that the highest plasma progesterone concentration was achieved differed among E3 and GnRH groups, occurring later in females treated with estradiol. In conclusion, an injection of estradiol-17β is capable of inducing ovulation in llamas and the response depends on the dose used. Most of the animals required the highest tested dose (1.6 mg) to induce the ovulatory process. Although the CL diameter in females induced to ovulate with estradiol was similar to that in llamas induced to ovulate with a GnRH analog, the rise in plasma progesterone concentration above 1 ng ml⁻¹ and the peak progesterone concentration were attained 1 day later in the estradiol treated females.

Factors affecting pregnancy rates and pregnancy losses after embryo transfer in dromedary camels

The present study was conducted to estimate incidence of late embryonic and early fetal mortalities (LEM/EFM) after embryo transfer (ET) and to investigate factors that could affect proportions of LEM/EFM in dromedary camels. The uteri of 180 donors were flushed at Day 9 post-mating and 1309 ETs were conducted in 886 recipient females in two breeding seasons (2014-2015 and 2015-2016). Pregnancy diagnosis was conducted at Day 10 after ET (Day 19 of gestation) by using the progesterone-ELISA test and by transrectal ultrasonography at Day 60 of gestation. Pregnancy rates at Days 19 and 60 and proportions of LEM/EFM were 54.5%, 34.1%, and 37.5%, respectively. Using logistic regression analysis for evaluations, shape of embryos had an effect (P < 0.01) on pregnancy rates at Days 19 and 60. Also, number of recovered embryos per uterine flushing and breeding season (year) had an effect (P < 0.05) on pregnancy rates at Day 19 and 60, respectively. Regarding rate of LEM and EFM, size of embryos and year of ET had effects (P < 0.01 and P < 0.05, respectively) on the values for these variables. In conclusion, there is a marked occurrence of LEM/EFM in recipient females between Days 20 and 60 of gestation in dromedary camels. The pregnancy rate after ET might be affected by the shape and number of recovered embryos and the year. In addition, the rate of LEM/EFM after ET might be affected by the year and size of the embryos.

Efficient follicular wave synchronization using a progesterone-releasing intravaginal device (PRIDΔ) in Camelus dromedarius

The reproductive efficiency of camels can be improved using artificial insemination and embryo transfer programs that require a dependable method for synchronization of follicular waves. This study aimed to evaluate the efficacy of a progesterone-releasing intravaginal device (PRIDΔ^®) to induce synchronization for the follicular wave in Camelus dromedarius during the rutting season, by ovarian monitoring, assessing sexual receptivity and fertility, and quantifying progesterone (P4) and estradiol (E2) concentrations. Twenty animals received a new PRIDΔ with 1.55 g of P4 for 2 wk (Day 14); another 20 camels were used as the control. Ultrasound ovarian monitoring and camel sexual receptivity were evaluated each day during the course of the experiment for all camels in the two groups. The proportion of animals in the ovulatory (follicle diameter: 12 to 18 mm) and non-ovulatory phases was calculated according to the ovarian monitoring results using ultrasound. Blind natural mating occurred on Day 16, and ovulation, non-return, and fertility rates were calculated. Blood samples were collected. Serum P4 and E2 levels were measured daily during the trial period (21 d) using ELISA kits. The results revealed that the proportion of females in the ovulatory phase on Day 16 in the PRIDΔ group was significantly higher than that in the control group (85 and 50, respectively). Serum P4 levels increased significantly after PRIDΔ insertion and reached the maximum values (5.47, 5.02, 5.55, and 4.88 ng/mL) on Days 4, 5, 6, and 7, respectively. P4 levels significantly decreased after PRIDΔ removal and reached the minimal levels (1.23 and 0.67 ng/mL) on Days 15 and 16, respectively. There was no significant difference in the E2 levels between the groups. Ovulation, non-return, and fertility rates in inseminated camels were significantly higher in the PRIDΔ group (85%, 80%, and 75%, respectively) than in the control group (50%, 45%. and 45%, respectively). In the control group, the P4 level was maintained at a minimal level (≥1 ng/mL). In conclusion, the treatment of dromedary camels with PRIDΔ led to a uniform increase in serum concentrations of P4; however, it could not stop follicular growth. After PRIDΔ removal, P4 concentrations dropped and stimulated the development of a new follicular wave; most female camels were in the ovulatory phase 2 d after PRIDΔ removal. Therefore, PRIDΔ is efficient at inducing follicular wave synchronization in C. dromedarius with good fertility.

Monitoring and controlling follicular activity in camelids

This paper reviews that state of our knowledge concerning follicular wave dynamics, monitoring and manipulation. All camelids have overlapping follicular waves in absence of ovulation which is induced by a seminal plasma factor (βNGF). The interval between follicular waves varies. The size of the ovulatory follicle varies between 11 and 25 mm in camels and between in 6 and 13 mm in South American Camelids. The interval between induction of ovulation and next ovulatory follicle is 15 ± 1 day for all camelids. Follicular activity is best monitored by transrectal ultrasonography. Progesterone therapy for 7-15 days seems to suppress follicular dominance but does not completely inhibit follicular recruitment. Combination of estradiol and progesterone seems to provide better control of follicular activity. Both methods have provided variable results in the synchronization of follicular waves. Combination of induction of ovulation with GnRH and luteolysis at predetermined times shows some promise in synchronization of follicular dominance. These synchronization protocols require further investigation in order to provide practical approaches for fixed-time breeding. Ovarian superstimulation with FSH and eCG alone or in combination is somewhat successful. The best results are obtained when treatment is initiated at the emergence of a new follicular wave after induction of ovulation or following treatment with progesterone for 7-14 days. However, response remains extremely variable particularly in terms of ovulation rate and number of recovered embryos. Sources of this variability need to be studied including the effects of season, nutrition, doses and frequency of administration of gonadotropin.

Confocal fluorescence assessment of bioenergy/redox status of dromedary camel (Camelus dromedarius) oocytes before and after in vitro maturation

BACKGROUND

Reproductive biotechnologies in dromedary camel (Camelus dromedarius) are less developed than in other livestock species. The in vitro maturation (IVM) technology is a fundamental step for in vitro embryo production (IVP), and its optimization could represent a way to increase the success rate of IVP. The aim of the present study was to investigate the bioenergy/oxidative status of dromedary camel oocytes before and after IVM by confocal microscopy 3D imaging.

METHODS

Oocytes were retrieved by slicing ovaries collected at local slaughterhouses. Recovered oocytes were examined before and after IVM culture for nuclear chromatin configuration and bioenergy/oxidative status, expressed as mitochondria (mt) distribution and activity, intracellular Reactive Oxygen Species (ROS) levels and distribution and mt/ROS colocalization.

RESULTS

The mean recovery rate was 6 oocytes/ovary. After IVM, 61% of oocytes resumed meiosis and 36% reached the Metaphase II stage (MII). Oocyte bioenergy/redox confocal characterization revealed changes upon meiosis progression. Immature oocytes at the germinal vesicle (GV) stage were characterised by prevailing homogeneous mt distribution in small aggregates while MI and MII oocytes showed significantly higher rates of pericortical mt distribution organized in tubular networks (P<0.05). Increased mt activity in MI (P<0.001) and MII (P<0.01) oocytes compared to GV stage oocytes was also observed. At any meiotic stage, homogeneous distribution of intracellular ROS was observed. Intracellular ROS levels also increased in MI (P<0.01) and MII (P<0.05) oocytes compared to GV stage oocytes. The mt/ROS colocalization signal increased in MI oocytes (P<0.05).

CONCLUSIONS

This study provides indications that qualitative and quantitative indicators of bioenergy and oxidative status in dromedary camel oocytes are modified in relation with oocyte meiotic stage. These data may increase the knowledge of camel oocyte physiology, in order to enhance the efficiency of IVP procedures.

Characterization of the estrous cycle in female beluga (Delphinapterus leucas) using urinary endocrine monitoring and transabdominal ultrasound: Evidence of facultative induced ovulation

Recent, successful application of assisted reproductive technologies in captive beluga has resulted from the extensive study of male beluga reproductive biology. Optimization of assisted reproduction requires additional detailed knowledge of the female estrous cycle. Our specific objectives were to: (1) validate urinary immunoassays for use in this species; (2) elucidate annual ovarian cycle dynamics through the combined use of hormone excretion patterns and transabdominal ultrasound; and (3) establish whether ovulation in this species is spontaneous or induced by male factors. Ovulation was observed in four of 15 estrous cycles monitored in four adult female beluga maintained in a single-sex group. After introduction of a breeding male, ovulation was observed in six of seven estrous cycles. All estrous cycles occurred from March through June. For spontaneous ovulations (n=4), the inter-estrous interval was 34d (range 33-35d), with a follicular phase length (FPL) of 25±8d (mean±SD). For all ovulatory estrous cycles (with and without a breeding male), urinary estrogen conjugates (EC, 15.3±7.9ng/mg Cr) and ovulatory luteinizing hormone (ovLH, 17.1±6.6ng/mg Cr) concentrations both peaked on Day 0, and EC concentrations returned to baseline 8±7d later. For non-conceptive cycles, urinary progestagen (Pg) concentrations increased on Day 0 (3.5±1.7ng/mg Cr), peaked on Day+19 (19.7±17.1ng/mg Cr), and were elevated above baseline for 27±4d. Preovulatory follicular diameter and circumference on Day -2±2 (range: Day -4 to -1) from peak EC were 2.5±0.7 and 7.8±1.3cm, respectively. The FPL in non-ovulatory estrous cycles (n=11) lasted 24±10d and EC concentrations gradually declined to baseline over a 21±10d interval following the EC peak (27.8±28.8ng/mg Cr). Non-ovulatory estrous cycles were characterized by the absence of an ovLH surge and no concomitant increase in Pg concentrations above baseline excretion; the mean follicular diameter at or near peak EC was 3.1±0.8cm on Day 2 ±3d from peak EC (range: -1 to +5days from peak EC). Overall, these data confirm that captive beluga exhibit reproductive seasonality and demonstrate that the species is a facultative-induced ovulator.

Acute stress may induce ovulation in women

BACKGROUND

This study aims to gather information either supporting or rejecting the hypothesis that acute stress may induce ovulation in women. The formulation of this hypothesis is based on 2 facts: 1) estrogen-primed postmenopausal or ovariectomized women display an adrenal-progesterone-induced ovulatory-like luteinizing hormone (LH) surge in response to exogenous adrenocorticotropic hormone (ACTH) administration; and 2) women display multiple follicular waves during an interovulatory interval, and likely during pregnancy and lactation. Thus, acute stress may induce ovulation in women displaying appropriate serum levels of estradiol and one or more follicles large enough to respond to a non-midcycle LH surge.

METHODS

A literature search using the PubMed database was performed to identify articles up to January 2010 focusing mainly on women as well as on rats and rhesus monkeys as animal models of interaction between the hypothalamic-pituitary-adrenal (HPA) and hypothalamic-pituitary-gonadal (HPG) axes.

RESULTS

Whereas the HPA axis exhibits positive responses in practically all phases of the ovarian cycle, acute-stress-induced release of LH is found under relatively high plasma levels of estradiol. However, there are studies suggesting that several types of acute stress may exert different effects on pituitary LH release and the steroid environment may modulate in a different way (inhibiting or stimulating) the pattern of response of the HPG axis elicited by acute stressors.

CONCLUSION

Women may be induced to ovulate at any point of the menstrual cycle or even during periods of amenorrhea associated with pregnancy and lactation if exposed to an appropriate acute stressor under a right estradiol environment.

Incidence of ovulation without coital stimuli in captive Japanese black bears (Ursus thibetanus japonicus) based on serum progesterone profiles

The purpose of this study was to ascertain whether or not Japanese black bears (Ursus thibetanus japonicus) are induced ovulators. The progesterone levels of female bears kept with a male and allowed to mate (n=2) and female bears allowed contact with a male through bars but not allowed to mate (n=6) during the mating season increased significantly in late October. Based on this result, the female bears were considered to have ovulated. Females isolated from males (n=3) were ovarioectomized after the mating season, and no corpora lutea were observed, indicating they had not ovulated. These findings suggest that Japanese black bears may be induced ovulators that ovulate with stimuli from males and without coitus at a high rate.