Follicle Wave Research Articles

Treatment alternatives to induce follicular wave emergence for timed-AI in lactating dairy Cows

Two experiments evaluated the effect of different hormonal treatments to synchronize follicle wave emergence on follicle dynamics and pregnancies per AI (P/AI) in estradiol (E2)/progesterone (P4) timed-AI (TAI) protocols in lactating dairy cows. In Experiment 1, lactating, primiparous Holstein cows (n = 36) received a P4 releasing device (Day 0) and were allocated at random to one of the following three treatment groups: Group EB received 2 mg E2 benzoate (EB) intramuscularly (i.m.), Group EB + GnRH received 2 mg EB+20 μg buserelin (GnRH) i.m., or Group EB + P4 received 2 mg EB + 100 mg of injectable P4 (iP4) in oil i.m. All cows received 0.150 mg D-Cloprostenol on Days 7 and 8 followed by P4 device removal, 400 IU eCG and 1 mg ECP on Day 8. Daily ultrasound examinations revealed that although the interval from P4 device removal to ovulation was not affected by treatment, cows that received EB + GnRH had an earlier (P < 0.05) emergence of the new follicular wave (Day 2.6 ± 0.2) than the other two treatment groups (Days 3.5 ± 0.3 and 6.1 ± 0.3, for EB and EB + P4, respectively). In Experiment 2, 808 lactating cows were assigned randomly to the three treatments evaluated in Experiment 1, and all the cows were TAI to determine P/AI. Cows in the EB + GnRH group had greater P/AI (57.4 %, P < 0.01) than those in the EB (44.6 %) or EB + P4 (45.7 %) groups. In conclusion, the administration of GnRH, but not iP4, on the day of insertion of a P4 device improves P/AI in lactating dairy cows synchronized for TAI with an estradiol/P4-based protocol.

ERβ Regulation of Indian Hedgehog Expression in the First Wave of Ovarian Follicles.

Increased activation of ovarian primordial follicles in Erβ knockout (ErβKO) rats becomes evident as early as postnatal day 8.5. To identify the ERβ-regulated genes that may control ovarian primordial follicle activation, we analyzed the transcriptome profiles of ErβKO rat ovaries collected on postnatal days 4.5, 6.5, and 8.5. Compared to wildtype ovaries, ErβKO ovaries displayed dramatic downregulation of Indian hedgehog (Ihh) expression. IHH-regulated genes, including Hhip, Gli1, and Ptch1, were also downregulated in ErβKO ovaries. This was associated with a downregulation of steroidogenic enzymes Cyp11a1, Cyp19a1, and Hsd17b1. The expression of Ihh remained very low in ErβKO ovaries despite the high levels of Gdf9 and Bmp15, which are known upregulators of Ihh expression in the granulosa cells of activated ovarian follicles. Strikingly, the downregulation of the Ihh gene in ErβKO ovaries began to disappear on postnatal day 16.5 and recovered on postnatal day 21.5. In rat ovaries, the first wave of primordial follicles is rapidly activated after their formation, whereas the second wave of primordial follicles remains dormant in the ovarian cortex and slowly starts activating after postnatal day 12.5. We localized the expression of Ihh mRNA in postnatal day 8.5 wildtype rat ovaries but not in the age-matched ErβKO ovaries. In postnatal day 21.5 ErβKO rat ovaries, we detected Ihh mRNA mainly in the activated follicles in the ovaries' peripheral regions. Our findings indicate that the expression of Ihh in the granulosa cells of the activated first wave of ovarian follicles depends on ERβ.

Ovarian follicular waves in ovulation induction in assisted reproduction techniques

Background: A greater understanding of the menstrual cycle and multiple waves of antral ovarian follicular development has challenged traditional concepts of female reproductive physiology and the foundations of assisted reproductive technologies (ART). Approximately two-thirds of women develop two follicle waves throughout an interovulatory interval, and the remainder exhibit three waves of follicle development. Major and minor waves of follicle development have been observed. Major waves are those in which a dominant follicle develops; dominant follicles either regress or ovulate. In minor waves, the physiological selection of a dominant follicle is not manifested. Knowledge of the waves of antral follicular development has led to the global adoption of novel ovarian stimulation strategies in which stimulation can be initiated at various times throughout the cycle. Random-start and luteal-phase ovarian stimulation regimens have important clinical applications in women requiring urgent oocyte or embryo cryopreservation for fertility preservation before chemotherapy.&#x0D; Objective: To evaluate the role of multiple waves of the antral ovarian follicular in the menstrual cycle in ovulation induction in ART.&#x0D; Methods: A literature search using the keywords “multiple waves of antral ovarian follicular development, In Vitro Fertilization, Ovarian stimulation ” was performed in the PubMed database.&#x0D; Outcome: Random start and luteal phase of ovulation induction in ART offer the same results in fertilization and pregnancy rates as conventional early follicular phase start.&#x0D; Conclusion: The primary benefits of the random-start protocol include a patient-oriented approach to care, timely and efficient treatment, and a lower dropout rate. Women with poor ovarian reserve and those diagnosed with cancer will have a greater chance of successful assisted reproduction with the use of these strategies.

Exploring AMH levels, homeostasis parameters, and ovarian primordial follicle activation in pubertal infected sheep on a high-protein diet

“Exploring AMH Levels, Homeostasis and Primordial Follicle Activation in Pubertal Infected Sheep on a High Protein Diet “.The first activation wave of ovarian primordial follicles is part of the onset of puberty and fertility. Abomasal helminth infection may cause an undesirable delay in puberty manifestation. Helminth-infected animals demand a higher amount of protein in their diet to repair the damage caused by the parasite in sheep's tissues, replenish the blood losses, and build the host's immune response. Helminths become resistant to drug therapy shortly after being exposed to a new treatment. Besides, there is the possibility of contamination by anthelmintic drugs in ovine products, possibly affecting human health and the environment. This study's objective was to evaluate if ovarian and clinical parameters can be improved by supplementing their diet with protein, offering a more sustainable management approach than relying on anthelmintic usage. We used a 2 × 2 factorial model where eighteen ewe lambs (Ovis aries) between 6 and 7 months old - born to the same ram - were fed one of two diet protein levels (12% or 19%). After 35 days on this diet, they were infected or left uninfected with 10,000 Haemonchus contortus L3 larvae. We evaluated Anti-Mullerian Hormone serum levels, blood cells and biochemical parameters at four different time points. Following 42 days of infection and 77 days on the diet, the lambs had their left ovaries removed, and we examined ovarian morphometrics through histological analysis. The groups Supplemented Protein-Infected(n = 5), Control Protein- Infected(n = 5), Supplemented Protein-Not Infected (n = 4) and Control Protein-Not Infected (n = 4) did not differ in their bodyweight gain. In the factorial ANOVA analysis examining the relationship between plasma protein, diet, and infection, the protein level of the diet showed significance (p = 0.02). Primordial follicle size varied with the interaction between diet and infection (p < 0.05), and oocyte size was affected by the level of protein in the diet (p = 0.047). Additionally, to understand how all homeostasis parameters relate to the primordial follicle and oocyte size, we applied an explanatory linear mixed model. In conclusion, serum AMH levels remained stable despite the infection and variations in diet protein levels, indicating its reliability as a marker for ovarian reserve in pubertal sheep. The number of blood cells, biochemical parameters, and primordial follicle activation were affected by both diet and infection.

Effects of mycobacterium cell wall fraction on embryo development following in vitro embryo production and pregnancy rates following embryo transfer in virgin dairy heifers

An experiment was conducted to determine whether administration of mycobacterium cell wall fraction (MCWF; Amplimune, NovaVive) could enhance embryo developmental competence following in vitro embryo production (IVP) and pregnancy establishment after embryo transfer (ET). Nulliparous, Holstein heifers (n = 40; age 8–15 months) were submitted to two rounds of ovum pick-up (OPU) and IVP in a crossover design. Thirty-six h after follicle wave synchronization, treatments (saline or MCWF, 5 mL, im) were administered in conjunction with a single dose of follicle stimulating hormone (175 IU) and OPU was performed 48–52 h later. Recovered cumulus-oocyte complexes were used for IVP to assess embryo development. For ET, nulliparous, Holstein heifers (n = 225; age 12–18 months) were used as recipients. At 12–24 h after detection of spontaneous estrus, recipients were randomly treated with either saline or MCWF (5 mL, im). The effect of MCWF on pregnancy per ET (P/ET) was assessed in a 2 × 2 factorial design with recipients treated with or without MCWF receiving a fresh IVP embryo from a donor treated with or without MCWF at day 7 or 8 after detected estrus. Blood samples were collected from a subset of donors (n = 8) and recipients (n = 26 to 33 per treatment) prior to treatment and at 6 and 24 h post-treatment to determine serum concentration of interleukin (IL)-1β, IL-6, tumor necrosis factor-α, and interferon-γ. Blood samples were also collected from a group of recipients (n = 31 to 39 per treatment) to assess serum concentration of progesterone at days 4, 7, and 16 post-treatment. Pregnancy status was determined at days 40 and 100 of gestation. Donor treatment with MCWF tended (P < 0.07) to increase the proportion of oocytes that developed into transferable embryos, but there was no effect of MCWF on other parameters of embryo development. The P/ET at days 40 and 100 of gestation and pregnancy loss were not affected by donor treatment or recipient treatment with MCWF and there was no interaction. Serum concentration of proinflammatory cytokines among donors and recipients and serum concentration of progesterone among recipients were not increased by treatment with MCWF. Results of the present study indicate that treatment of donors with MCWF has minimal impact on subsequent embryo development following IVP. Moreover, regardless of whether donors or recipients were treated with MCWF, there was no effect on P/ET following transfer of IVP embryos.

Characterization of Postpartum Ovarian Follicular Development Pattern in Crossbred Cows

Background: The postpartum period is crucial for cattle reproduction. The length of postpartum anestrus significantly impacts reproductive efficiency. Apparently enhanced energy attribution to milk production may lead to anestrus by delaying the onset of follicular activity. The absence of an ovulation stimulus, rather than insufficient follicle growth, determines the limited duration until ovulation. The current study was aimed to document the postpartum ovarian dynamics in crossbred Jersey cows. Methods: The study was conducted in ten postpartum crossbred Jersey cows. Transrectal ultrasonography was performed to record the follicular development pattern from parturition till two ovulation or 90 days postpartum on alternate days. The data was analyzed for follicular wave emergence, no of follicular waves, size of the dominant follicle and ovulatory status. Result: Fourty per cent of crossbred Jersey cows showed cyclicity and rest 60 per cent of cows are in anestrum. The mean diameter size of the dominant follicle in ovulated cows is 12.2±1.2 mm and in anestrum cows is 10.6±0.4 mm. The first wave emergence is 5.7±0.3 and 10.8±5.9 day in OV and NOV group respectively. In conclusion significant difference could be observed in emergence of first, second, third, fourth and fifth follicular wave emergence, growth phase duration, rate, size of the dominant follicle and duration of wave between postpartum ovulated and anestrum cows.

Estrus and ovulation synchrony of buffaloes (Bubalus bubalis): A review

Synchronizing estrus and ovulation in buffalo using timed inseminations (TAI) protocols circumvents the limitations associated with estrus detection. Spontaneous estrus in buffalo may achieve more conception rate on insemination than those subjected to synchronization of estrus and timed insemination (TAI). The advantages of insemination following synchronization programs include higher detection rates combined with decreased embryonic losses and reduction in days open. A synchonization programme should ensure control of estrus cycle which entirely depends on ovarian status of animals before starting any protocol. Ovarian follicular status at the beginning of treatment protocols plays vital role for effective response shown by animals. Studies show that more precise alterations in follicular waves may be needed to achieve better synchrony of ovulation and more fertility. The protocols which use Gonadotropic Releasing Hormone (GnRH), follicle stimulating hormone (FSH), luteinizing hormone (LH), equine chorionic gonadotropin (eCG), human chorionic gonadotropin (hCG), prostaglandins, progesterone and estradiol have been helpful in achieving the estrus and ovulation synchrony. Use of estradiol esters and progesterone per-vaginum implants have also been incorporated in synchronization programs. Synchronous emergence of follicular waves using trans-vaginal ultrasound guided follicular ablation and estradiol administration is a recent concept for synchronization in buffalo. Further, a recent approach has been to allow the follicle of second follicular wave to ovulate as the fertility has been lesser when first wave follicle ovulates. Moreover, controlling environmental influences, nutritional and managemental strategies remain pre-requisite to achieve desired goals though hormonal administration. This is more particular in buffaloes suffering from anestrum more so in low or non-breeding season and pre-pubetal anestrum. This review will cover the available documented literature regarding estrous cycle physiology with emphasis on follicular wave dynamics and the future area of work to be focused to achieve more reproductive efficiency in buffalo.

Preantral follicle numbers and size in heifers carrying Trio, a bovine high fecundity allele.

The bovine high fecundity allele, Trio, results in the occurrence of multiple ovulations and is characterized by antral follicles that develop slower and acquire ovulatory capacity at smaller sizes. This study provides novel information on the effect of the Trio allele on early folliculogenesis. The bovine high fecundity allele, Trio, causes overexpression in granulosa cells (GCs) of SMAD6, an inhibitor of BMP15-activated SMAD signalling. Furthermore, the Trio allele results in antral follicles that develop slower, acquire ovulatory capacity at smaller sizes, and have three-fold greater ovulation rate compared to half-sib non-carriers. The present study was designed to determine preantral follicle numbers and size in Trio carrier and non-carrier cattle testing the hypothesis that inhibition of SMAD signalling would alter preantral follicle activation and/or growth. Ovarian tissues from Trio carrier (n = 12) and non-carrier (n = 12) heifers were obtained by laparotomy after follicle wave synchronization. Follicle numbers and dimensions were determined for each stage of development (primordial, transitional, primary, and secondary) from paraffin-embedded sections. There were no differences in the number of primordial, transitional, or secondary follicles or in antral follicle count, circulating AMH, or ovarian volume between carriers and non-carriers. Trio carriers had ~2.5-fold greater (P < 0.01) number of primary follicles than non-carriers, and transitional and primary follicles were larger (~1.2-fold; P < 0.1) in Trio carriers. Oocyte volume of primordial and transitional follicles was not different between genotypes; however, oocytes were larger (P < 0.05) in primary (~1.3-fold) and secondary (~1.8-fold) follicles for Trio carriers. Granulosa cell numbers were not different (P > 0.3) between carriers and non-carriers, irrespective of the stage of development. These results suggest that, after primordial follicle activation, follicles in Trio carrier cattle have slower progression through the primary stage, hence the larger oocyte and greater number of primary follicles.

Quantitative Histomorphometry of Pre-ovulatory Follicles and Uterine Glands of Ongole-grade Heifer in Response to the Low Doses of PMSG Administration

Injection of female mammalian animals with gonadotropin prior to mating using superovulation dose increases estradiol 17beta (E2) synthesis and secretion and improves the growth and development of the uterus to support prenatal growth with the side effect of increasing litter size. This experiment was designed to study the effects of low doses of PMSG injection in heifers on the growth of granulose cells (GC) of pre-ovulatory follicles, E2 synthesis, and uterine glands growth and development. Nine Ongole-grade heifers were divided into three groups of doses of PMSG injection, i.e., 0 IU/kg BW, 0.5 IU/kg BW, and 1.0 IU/kg BW. The injection of pregnant mare serum gonadotropin (PMSG) was conducted at the early stage of the second follicle wave. Blood samples were collected at estrus (day 0) to measure plasma E2 concentrations. The ovary and uterus were collected for histological observation after slaughtering the animal. The results showed that non-superovulation doses of PMSG injections at the second follicle wave significantly increased the growth of GC that eventually produced a significantly higher plasma E2 concentration by 39.47% and 113.57%, in heifers receiving 0.5 IU/kg BW and 1.0 IU/kg BW (p<0.05), respectively. The increase in E2 synthesis and secretion significantly stimulated the growth and development of uterine glands (p<0.05), which was reflected in the improved measures of uterine glands. In conclusion, injections of heifers with low doses of PMSG at the second follicle wave could increase the growth of GC to produce a higher secretion of E2 that eventually improves the growth and development of uterine glands in the endometrium without the risk of multiple calving.

The Use of Ultrasound for Monitoring the Relationship Between the Diameter of the Dominant Follicle, The Inter-ovulatory Interval, and Follicular Waves in Dairy Cattle

The aim of the current study was to use ultrasound imaging to follow the follicular dynamics in dairy cows and to determine the relationship between the diameter of the dominant follicle (DF), the life span of the corpus luteum (CL), interovulatory interval (IOI), and the number of follicular waves. Twenty nine Holstein normal cyclic cows 60 days postpartum were used in this study. The ovaries of the experimental cows were scanned for the DF and CL every three days from ovulation to ovulation. Cows undergo the Ovsynch program to unify the beginning of the ovulation per cycle. The results revealed that, cows that exhibit the two wave patterns have a longer time of IOI than a cow with a one wave pattern (P&lt;0.05), and a shorter length of IOI than cows with three follicular wave patterns (P&lt;0.05). The duration of the DF growth phase in the first follicular wave (Wave 1) was prolonged in a cow that exhibited a one-wave pattern than in the cows that exhibited the two or three-wave patterns (p&lt;0.05). The maximum diameter of DF for a single follicular wave pattern (17.6 ± 0.67 mm). The maximum diameter of the anovulatory follicle in the two-wave patterns (12 ± 2.53 mm) was larger than the maximum diameter of the anovulatory follicle (10.75 ±1.33 mm, p&lt;0.05) of wave one in cows that exhibited three-wave patterns. The lifespan of the corpus luteum in the one-wave pattern was significantly shorter (p&lt;0.05) than in two-wave patterns and three-wave patterns. The length of the IOI was positively increased with the number of the follicular wave and the length of the luteal phase but was negatively related to the diameter of the first dominant follicle in the wave and the duration of the (DF) growth phase in the first wave (p&lt;0.05). In Conclusion, these results demonstrate that the length of the IOI in cows exhibiting the two-wave patterns is shorter than in cows exhibiting three-wave patterns due to the larger diameter of the dominant follicle in wave one, the longer duration of the DF growth phase in the first wave, and the shorter life span of the CL in the cows exhibiting two-wave patterns than in cows exhibiting three-wave patterns.

153 Assessment of methods to synchronise follicle wave emergence in pregnant heifers

Reproduction, Fertility and Development is an international journal publishing original research , review and comment in the fields of reproduction and developmental biology in humans, domestic animals and wildlife

Ovarian follicle dynamics in ewes treated with intra-vaginal progesterone pessaries. 1. Follicle waves and parameters of the estrous cycle

Progesterone treatment for synchrony of estrus is standard in sheep artificial insemination (AI) programs but can be associated with poor outcomes. Potential for improvement exists through a better understanding of the interactions between follicle development, luteal regression, emergence of the ovulatory follicle and timing of estrus. These interactions were examined by comparing progesterone-treated (Day 1 = day of pessary insertion) and naturally cycling ewes (Day 1 = day after estrus) at three times of the year (Autumn, Spring equinox and late Spring). Observations were made from Day 1 until the day of ovulation. Compared with the natural cycle, progesterone treatment (300 mg intra-vaginal pessary for 14 d) reduced the number of follicle waves (2.2 ± 0.18 versus 2.8 ± 0.12; P < 0.05) and increased the length of the ovulatory wave (8.6 ± 0.45 versus 6.6 ± 0.42 d; P < 0.05). The number of follicles per wave, the inter-wave interval and ovulation rate were not affected. However, progesterone treatment induced (P < 0.05) an earlier luteolysis (9.7 ± 0.51 versus 15.4 ± 0.49 d after Day 1), an earlier emergence of the ovulatory follicle (7.5 ± 0.48 versus 11.4 ± 0.46 d after Day 1) and an earlier onset of estrus (26.1 ± 2.95 versus 53.3 ± 2.84 h after Day 14). Time of year also influenced the response to progesterone treatment. In Autumn compared with the Spring equinox and late Spring, there was a reduction (P < 0.05) in follicle wave number (2.4 ± 0.21 versus 2.5 ± 0.29 versus 3.0 ± 0.20 respectively), follicles per wave (2.6 ± 0.27 versus 3.5 ± 0.25 versus 3.2 ± 0.20 respectively), ovulation rate (1.6 ± 0.12 versus 1.9 ± 0.12 versus 2.0 ± 0.10 respectively) and the inter-wave interval was longer (5.3 ± 0.40 versus 4.0 ± 0.32 versus 3.8 ± 0.27 d respectively; P < 0.05). Time of year also influenced (P < 0.05) the time of luteolysis (earliest in late Spring), emergence of the ovulatory follicle (earliest in Autumn) and onset of estrus (earliest in Autumn). It is concluded that (1) the effects of progesterone treatment on follicle waves are relatively minor, (2) the effects of treatment on timing of luteolysis, emergence of the ovulatory follicle and onset of estrus are all significant although the effects on AI outcomes remain to be determined and (3) time of year has a minimal effect on follicle waves but a more significant effect on other parameters of the estrous cycle. A better understanding of these complexities will assist in the development of improved protocols for synchrony of estrus.

Follicular Dynamics and Endocrine Profile during Normal Estrous Cycle and Early Pregnancy in Surti Buffaloes

The study was conducted on Surti buffaloes for follicular dynamics and endocrine profile during normal estrous cycle (n=6) and early pregnancy (n=6). In cyclic and early pregnant buffaloes, one-wave (33.33% vs. 50.00%) and two-waves (66.66% vs. 50.00%) follicular development was recorded, without three-wave pattern. In cyclic buffalo, the length of estrous cycle and duration of inter-ovulatory interval were little shorter in one wave cycles than in two wave cycles (22.50±0.50 and 23.25±0.25 days). The number of follicles differed non-significantly within and between cyclic and early pregnant buffaloes. The mean maximum diameter of dominant follicle of second wave was significantly larger in cyclic than early pregnant animals for two wave pattern (1.09±0.02 vs 0.73±0.02 cm). In cyclic buffaloes, the mean maximum CL size recorded was 1.21±0.02 and 1.52±0.05 cm (P&lt;0.05) in one- and two-wave cycles, respectively, whereas in early pregnant buffaloes, the corresponding CL size was 1.50±0.04 and 1.55±0.07 cm without significant difference. Thus the mean maximum CL size of early pregnant buffaloes was significantly larger than the cyclic buffaloes with one-wave cycle (1.50±0.04 vs. 1.21±0.02 cm). In the normal cyclic animals, the CL size increased gradually up to day 8 (1.30±0.04 cm) and then remained stable up to day 18 (1.26±0.15 cm), followed by regression and display of next estrus between day 19 and 21, whereas in early pregnant animals the CL size gradually increased up to day 10 (1.48±0.07 cm) and then it was maintained till day 22 (1.46±0.04 cm) of monitoring. The mean diameter of largest follicle recorded was on the day of estrus (0.98±0.07 cm) with variable development of follicles during metestrus to diestrus phase with a new follicles developed during proestrus to estrus phase reaching maximum diameter of ovulatory size (0.99±0.09 cm) between days 19 and 21, whereas in early pregnant animals, the diameter of larger follicle (0.76±0.05 cm) was not recorded up to ovulatory size. The mean concentrations of serum progesterone were lowest during peri-estrus phase, increased through early-luteal phase to a maximum concentration during mid-luteal phase (4.50±0.88 to 4.67±0.95 ng/ml) and then gradually declined through late-luteal phase of diestrus in normal cyclic animals with inverse trend in estradiol profile. However, in early pregnant animals the progesterone levels gradually increased initially and then were maintained higher (6.17±0.32 to 8.13±0.55 ng/ml) with basal estradiol throughout the luteal phase. The serum progesterone/estradiol levels were in harmony with the ovarian dynamics in both cyclic and early pregnant buffaloes. The mean concentrations of serum FSH, LH and kisspeptin in normal cyclic and early pregnant animals did not vary statistically between periods within the status or between reproductive status of animals at any of the periods. The concentration of serum kisspeptin dropped significantly in advanced pregnancy as compared to first and second trimester.

DuoStim: The Patient Experience of a Follicular and Luteal Phase Stimulation

Background: A dual stimulation, or ‘DuoStim’ protocol results in the recruitment of developing waves of antral follicles to occur one after the other within a menstrual cycle 1 . This proffers benefits for women who have previously demonstrated a poor response to assisted reproductive technologies, providing an opportunity to increase the number of oocytes collected, as well as for women aiming for fertility preservation 1 . Aim: We report on the experience of women who have undergone dual stimulation and oocyte pick up, in both the follicular and luteal phase of the cycle. Result: All women who underwent a DuoStim cycle at a single IVF centre in Victoria, Australia were invited to participate. Information was collected regarding experience and satisfaction across the domains of social, emotional, financial and alignment with fertility goals utilising a 5-point Likert Scale. Conclusion: Whilst dual stimulation protocols offer promising options for specific patient populations there remains a need to report on quality outcomes 2 .

Integration of transcriptomic and metabolomic analysis of the mechanism of dietary N-carbamoylglutamate in promoting follicle development in yaks.

Yak is the main livestock in the highlands of China. The low reproductive rate of yaks is a serious constraint on their production and utility. N-carbamylglutamate (NCG) can increase arginine synthesis in mammals and has been shown to improve reproductive performance. Twelve multiparous and simutaneous anoestrous female yaks were randomly divided into two groups, one of which was fed the basal diet (Control, n = 6), and the other was fed the basal diet supplemented with NCG at 6 g/day/yak (NCG, n = 6). All yaks were slaughtered on the 32nd day (the time predicted for the selection of the last wave of dominant follicles), and their ovarian tissues were collected and follicles were classified. NCG supplementation increased the number of large ovarian follicles (diameter > 10 mm), as well as caused significant changes in the transcriptional and metabolic levels in yak ovaries which due to the differential expression of 889 genes and 94 metabolites. Integrated analysis of the transcriptomics and metabolomics data revealed that the differentially expressed genes and differential metabolites were primarily involved in the process of energy metabolism, amino acid metabolic pathways, carbohydrate metabolic pathways, and lipid metabolic pathways. The highlighted changes were associated with amino acid synthesis and metabolism, ovarian steroid hormone synthesis, the pentose phosphate pathway, and the tricarboxylic acid cycle, suggesting that NCG supplementation may promote estrogen synthesis and help regulate follicular development by altering the pathways associated with glucose catabolism. The results present important clues for understanding the mechanisms by which NCG supplementation promotes follicular development in yaks. The findings of this study provide a basis for the development and application of NCG in optimizing animal reproduction, including yak reproductive performance, which may help optimize livestock management and uplift the pastoral economy.

Temporal evaluation of follicular dynamics and endocrine patterns of Holstein (Bos taurus), Gir (Bos indicus), and Murrah (Bubalus bubalis) heifers kept under the same nutritional, management and environmental conditions

The objective of the study was to simultaneously compare ovarian follicular dynamics and endocrine parameters of taurine (Holstein; n = 14), zebuine (Gir; n = 5), and bubaline (Murrah; n = 15) heifers kept under the same environmental, nutritional and management conditions. Heifers were synchronized with two PGF treatments 14 days apart. Ovaries of cyclic heifers were scanned daily during two consecutive ovulations and blood samples were collected every 24 h from each animal. No significant difference was found for length of interovulatory interval, however, zebuine heifers presented a greater number of follicular waves, number of antral follicles on day of ovulation, and higher insulin concentration than the other two breeds. Taurine heifers had highest maximal diameter of first wave dominant and ovulatory follicles and CL volume. Taurine and bubaline heifer's dominant follicle of first wave had longer static and regression phases than zebuine heifers. Bubaline heifers presented overall lowest progesterone concentrations and CL volume, but higher IGF1 levels. No difference was observed between taurine and zebuine heifers regarding IGF1 concentration. Despite higher CL volume found in taurine heifers, no difference in mean progesterone concentration was observed between them and zebuine heifers. Insulin and IGF1 concentrations were greater in follicular phase than in luteal phase when breed was not evaluated. After evaluating the three breeds simultaneously, at the same nutritional and management status it is possible to conclude that each genetic group has a specific follicular development and endocrinology of the estrous cycle.

Ovarian follicular dynamics, hormonal profiles and ovulation time in Mithun cows (Bos frontalis).

The study aimed to evaluate follicular dynamics and concentrations of estradiol-17β (E2), progesterone (P4), follicle stimulating hormone (FSH) and luteinizing hormone (LH) during the oestrous cycle and to determine ovulation time in Mithun cows. Ovaries of experimental cows (n=7) were examined daily by transrectal-ultrasonography for three consecutive oestrous cycles (n=21). The characteristics of follicular waves, dominant follicle, largest subordinate follicle and corpus luteum and ovulation time were evaluated. The plasma samples were analysed throughout the interovulatory interval to determine the differences in the hormonal profiles (E2, P4, FSH and LH) between different follicular wave cycles. Out of eighteen oestrous cycles analysed, three-wave follicular cycles were maximum (n=12: 66.66%) followed by two (n=4: 22.22%) and four waves (n=2: 11.11%). The two and three waves were statistically compared, and no significant (p > .05) differences were observed in day of wave emergence, number of follicles (≥3 mm) recruited, maximum diameter of the ovulatory dominant follicle, growth rates of ovulatory and anovulatory dominant follicles and maximum diameter of corpus luteum. The diameter of dominant follicles was significantly (p < .05) greater than subordinate follicles in both ovulatory and anovulatory waves. No significant differences were observed in peak concentrations of estradiol-17β and follicle stimulating hormone between ovulatory and anovulatory waves in all wave cycles. A preovulatory luteinizing hormone surge was observed a day before ovulation in all wave cycles. Progesterone concentrations were lower than 0.5ng/ml during oestrus and increased sharply to the maximum levels of ≥3.8ng/ml in all wave cycles. Ovulation time (mean ± SEM), irrespective of follicular waves was 10.5 ± 0.64 h after the end of oestrus. It was concluded that Mithun cows have a preponderance of three follicular waves with little difference between the two- and three-follicular waves and ovulation occurred 10.5h after the end of oestrus.

Synchronization of follicle wave emergence before ovarian superstimulation with FSH and ovum pick-up improves in vitro embryo production in pregnant heifers

The objective of the present study was to evaluate effects of synchronization of timing of follicle wave emergence, before ovarian superstimulation and ovum pick-up (OPU), on ovarian response and embryo production in pregnant heifers. Pregnant (47–69 days of gestation) Holstein heifers (n = 64), 19.0 ± 0.3 months of age, were assigned in a completely randomized design to one of two groups: synchronization of follicular wave emergence using follicle ablation (Synchronized) or untreated control (Non-synchronized). Superstimulatory treatments consisting of 160 mg (280 IU) of porcine follicle stimulating hormone (p-FSH), administered in four decreasing dose treatments 12 h apart, were initiated 36 h after follicle ablation or at random stages of the follicular wave in heifers of the Synchronized and Non-synchronized group, respectively. Ovum pick-up was performed in all heifers 40 h after the last p-FSH administration and retrieved cumulus oocyte complexes (COCs) were subjected to in vitro embryo production (IVEP) procedures. Ultrasonography was performed immediately before OPU to determine number and size of ovarian follicles. Differences in treatment responses between groups were evaluated using generalized linear mixed models. Total number of follicles at the time of OPU was not different between treatment groups (P = 0.61), however, the number of small follicles (<6 mm) was greater (P = 0.05) in heifers of the Non-synchronized group, whereas number of medium size follicles (6–10 mm) tended (P = 0.09) to be greater in heifers of the Synchronized group. Heifers in the Synchronized group had a greater (P = 0.01) percentage of medium sized follicles and a lesser (P = 0.01) percentage of smaller sized follicles than heifers in the Non-synchronized group. There were no differences (P > 0.15) in total number of recovered COCs, or number of viable COCs between groups. Cleavage percentage (84.5% and 72.8%) and blastocyst percentage (48.2% and 33.4%) were greater (P < 0.01) in heifers of the Synchronized than Non-synchronized group, respectively. As a result, mean number of blastocysts per OPU/heifer was greater (P = 0.006) in the heifers of the Synchronized (8.9 ± 1.0) than the Non-synchronized (5.5 ± 0.9) group. In conclusion, synchronizing the time of follicle wave emergence in pregnant heifers, prior to ovarian superstimulation with FSH and OPU results in a greater superstimulatory response and oocyte competence leading to greater embryo production.

Asynchronous embryonic germ cell development leads to a heterogeneity of postnatal ovarian follicle activation and may influence the timing of puberty onset in mice

BackgroundOvarian follicles, which are the basic units of female reproduction, are composed of oocytes and surrounding somatic (pre) granulosa cells (GCs). A recent study revealed that signaling in somatic preGCs controlled the activation (initial recruitment) of follicles in the adult ovaries, but it is also known that there are two waves of follicle with age-related heterogeneity in their developmental dynamics in mammals. Although this heterogeneity was proposed to be crucial for female reproduction, our understanding of how it arises and its significance is still elusive.ResultsIn the current study, by deleting the key secreted factor KIT ligand from preGCs and analyzing the follicle cell developmental dynamics, we revealed distinct patterns of activation and growth associated with the two waves of follicles in mouse ovary. Our results confirmed that activation of adult wave follicles is initiated by somatic preGCs and dependent on the KIT ligand. By contrast, activation of first wave follicles, which are awakened from germ cells before follicle formation, can occur in the absence of preGC-secreted KIT ligand in postnatal ovaries and appears to be oocyte-initiated. We also found that the asynchronous activity of phosphatidylinositol 3 kinases (PI3K) signaling and meiotic process in embryonic germ cells lead to the follicle heterogeneity in postnatal ovaries. In addition, we supplied evidence that the time sequence of embryonic germ cell development and its related first wave follicle growth are correlated to the time of puberty onset in females.ConclusionTaken together, our study provides evidence that asynchronous development of embryonic oocytes leads to the heterogeneity of postnatal ovarian follicle activation and development, and affects the timing of onset of puberty in females.

Hormonal regulation of ovarian follicle growth in humans: Model-based exploration of cycle variability and parameter sensitivities

We present a modelling and simulation framework for the dynamics of ovarian follicles and key hormones along the hypothalamic-pituitary–gonadal axis throughout consecutive human menstrual cycles. All simulation results (hormone concentrations and ovarian follicle sizes) are in biological units and can easily be compared to clinical data. The model takes into account variability in follicles’ response to stimulating hormones, which introduces variability between cycles. The growth of ovarian follicles in waves is an emergent property in our model simulations and further supports the hypothesis that follicular waves are also present in humans. We use Approximate Bayesian Computation and cluster analysis to construct a population of virtual subjects and to study parameter distributions and sensitivities. The model can be used to compare and optimize treatment protocols for ovarian hyperstimulation, thus potentially forming the integral part of a clinical decision support system in reproductive endocrinology.