Corpus Luteum Vascularization Research Articles

Association of Ovarian Structures, Uterine Characteristics and Cervico-vaginal Mucus Attributes with Conception in Dairy Cows

This study was conducted to evaluate the association between ovarian structures, uterine characteristics and physical attributes of cervico-vaginal mucus (CVM) with conception rate in normal cyclic dairy cows (N=20) at estrus. Different physical parameters of CVM at estrus such as quantity, consistency, color, pH, Spinnbarkeit value and fern pattern were evaluated. Transrectal ultrasonography was done at estrus to carry out the morphometry of follicles and uterine horns as well as following artificial insemination, the mid-cyclic corpus luteum size and functionality were assessed on the 10th day using B-mode and color Doppler ultrasonography. Among the physical parameters, significantly higher (p<0.05) Spinnbarkeit values were recorded for subsequently pregnant (n=12) as compared to non-pregnant cows (n=8). The mean diameter of the preovulatory follicle at estrus and corpus luteum vascularity (%) was significantly higher (p<0.05) in subsequently pregnant as compared to non-pregnant cows while, no significant difference (p>0.05) was recorded for intraluminal uterine fluid diameter and endometrium thickness. In conclusion, higher spinnbarkeit and preovulatory follicle diameter at estrus led to a better conception rate in dairy cows.

Influence of Age and Breed on Bovine Ovarian Capillary Blood Supply, Ovarian Mitochondria and Telomere Length

Worldwide, dairy cows of the type of high-producing cattle (HPC) suffer from health and fertility problems at a young age and therefore lose productivity after an average of only three lactations. It is still contentious whether these problems are primarily due to genetics, management, feeding or other factors. Vascularization plays a fundamental role in the cyclic processes of reproductive organs, as well as in the regeneration of tissues. In a previous study, HPC were shown to have a greater ovarian corpus luteum vascularization compared to dual-purpose breeds. We hypothesize that this activated angiogenesis could likely lead to an early exhaustion of HPC′s regenerative capacity and thus to premature reproductive senescence. The objective of this study was to investigate if a HPC breed (Holstein-Friesian, HF) exhibits higher ovarian angiogenesis than a dual-purpose breed (Polish Red cow, PR) and if this is related to early ovarian aging and finally reproductive failure. For this purpose, we assessed the degree of vascularization by means of ovarian blood vessel characterization using light microscopy. As indicators for aging, we measured ovarian mitochondrial size and telomere length in peripheral leukocytes. We report in this study that in both breeds the distance between capillaries became smaller with increasing age and that the mean telomere length decreased with increasing age. The only difference between the two breeds was that PR developed larger capillaries than HF. Neither a relationship between telomere length, nor the morphology of the mitochondrial apparatus and nor angiogenesis in HF was proven. Although the data trends indicated that the proportion of shortened telomeres in HF was higher than in the PR, no significant difference between the two breeds was detected.

Correlations of corpus luteum blood flow with fertility and progesterone in embryo recipient mares.

The aim of this study was to evaluate the correlation between the corpus luteum vascularization with the concentration of progesterone and the fertility of embryo recipient mares. Mangalarga Marchador mares (n = 33) were distributed into groups according to the days (D) after ovulation, as follows: D3 (n = 8), D4 (n = 8), D5 (n = 9), and D6 (n = 8). The evaluations of the corpus luteum, endometrium, and blood collection to quantify the progesterone concentration were carried out on D3, D4, D5, and D6. Among the parameters evaluated, only progesterone concentration on D6 differed from the other groups (P <0.05). A positive correlation (P <0.05) between the diameter and the area of the corpus luteum, and the objective and subjective methods of the corpus luteum vascular perfusion, was identified. Likewise, a positive correlation (P <0.05) was observed between the objective and subjective methods of the vascular perfusion in the corpus luteum and the progesterone concentration. The pregnancy rate obtained in this study (54.54%) was not affected (P> 0.05) by the day of embryo transfer, whose percentages were 37.50% (3/8) on D3, 50% (4/8) on D4, 66.70% (6/9) on D5, and 62.50% (5/8) on D6. It was estimated that with each increase on the day of embryo transfer, the pregnancy rate increases. The results allow to conclude that the corpus luteum vascularization in mares, evaluated by Doppler ultrasound, correlates with progesterone concentration and the embryo transfer day.

Evaluation of Corpus Luteum Vascularization in Recipient Mares by Using Color Doppler Ultrasound

Background: Embryo transfer is one of the most commonly used reproductive biotechnique. The success of embryo transfer is also affected by the synchrony of estrus and ovulation between donor and recipient animals. In horse reproduction, ultrasonography has been used, among other purposes, to diagnose early pregnancy. However, only the color Doppler imaging mode makes it possible to evaluate the vascular architecture and the hemodynamic aspects of the vessels in several organs, especially the corpus luteum. The objective of this study was to evaluate, based on the color Doppler ultrasound, the corpus luteum vascularization and function from recipient mares at embryo transfer timing.Materials, Methods &amp; Results: Mangalarga Machador mares from 5 to 10-year-old and a range of live weights of between 350 to 450 kg were used for this experiment, kept in pasture-based on mombaça grass (Panicum maximum) and were given ad libitum access to water and mineral supplementation. The animals (n = 15) were gynecologically examined and uterine consistency was evaluated by rectal palpation the same operator using an ultrasound system (SonoScape®) with a linear transducer, and operating frequency ranging from 5 to 10 Mhz. The uterine tone was classified between grades 1 and 4 and subjected to ovulation induction. The objective and subjective vascular perfusion of the corpus luteum was evaluated by color Doppler ultrasound on the day of embryo transfer and endometrium. The determination progesterone concentration on the day of the embryo transfer was performed by direct chemiluminescence assay. The arcsine (√P/100) transformation was applied to the percentage data, and the results were expressed as mean (.) ± standard error of the mean (SEM). Further, the assumptions of normality and homoscedasticity were verified, respectively, based on the Shapiro-Wilk and Lilliefors tests. Regarding the parametric and non-parametric variables, were applied, respectively, analysis of variance (ANOVA) followed by Tukey’s test, and the Kruskal-Wallis test followed by Dunn’s test. Pearson’s correlation coefficient was used to evaluate the relationship between the parameters. The statistical program SPSS 16.0 was used to perform the over-mentioned analyses, and a p-value &lt; 0.05 was taken as significant. Corpus luteum vascular perfusion, based on the objective and subjective evaluation methods, and the progesterone concentration were higher in the pregnant mares (P &lt; 0.05). The objective and subjective methods for evaluation of the vascular perfusion in the corpus luteum were positively correlated between themselves as well as to progesterone concentration (P &lt; 0.05). There was no significant difference between the groups considering the uterine tonus evaluation (P &gt; 0.05).Discussion: Mares that later became pregnant showed a higher concentration of progesterone as an outcome of the higher vascularization in the corpus luteum. It can be supported by both the correlation between the progesterone concentration and the corpus luteum vascular perfusion, as well as by the higher values of the vascular perfusion in pregnant mares. Based on the results, it has been concluded that the color Doppler ultrasound evaluation is an accurate tool to determine the corpus luteum vascularization, whether considering the objective or subjective methods. Also, the vascular perfusion is the most efficient parameter to determine both the corpus luteum function and to predict the ability of the recipient mares to maintain pregnancy.

Corpus luteum vascularization during the maternal recognition of pregnancy in llamas (Lama glama).

The aim of this study was to characterize corpus luteum vascularization and its association with plasma progesterone concentration in early stages of pregnancy, when maternal recognition of pregnancy is expected to occur. In all animals, both plasma progesterone concentration and corpus luteum vascularization increased from Day 6 to Day 8 post-mating and afterwards in non-pregnant llamas they started to decrease to reach basal levels around Days 12 to 14 post-mating, while in pregnant animals, both variables remained elevated until the end of the study. A lineal positive relationship between corpus luteum vascularization and plasma progesterone concentration was observed in pregnant (r2 =.46, p<.0001) and non-pregnant llamas (r2 =.66, p<.0001). Pregnant animals showed higher plasma progesterone concentration and corpus luteum vascularization than the non-pregnant ones from Day 12 post-mating until the end of the study (p˂.05 and p˂.01, respectively). These results suggest that maternal recognition of pregnancy should occur before Day 12 post-mating in order to expand luteal lifespan, maintaining corpus luteum vascularization and progesterone production. Also, the assessment of CL vascularization area could be a useful and non-invasive method for early pregnancy diagnosis due to its association with plasma progesterone concentration.

Effect of hCG application at different moments of the estrous cycle on corpus luteum and uterine vascularization and serum progesterone concentration in mares.

Establishment of pregnancy after embryo transfer is the ultimate goal of an embryo transfer program and increasing pregnancy rates and reducing pregnancy loss are mandatory. The utilization of treatments to improve conception rates in recipient mares has been the focus of several research groups over the last years and the results are controversial. Some studies using human chorionic gonadotrophin (hCG) found promising results. Our hypothesis was that hCG administration would cause an additional stimulation on luteal function, uterine and luteal vascularization and progesterone concentration, and the mares would have increased uterine and cervix tone. Therefore, in the present study the effects of hCG administration to induce ovulation, on day 0 (day of ovulation) or day 5 postovulation were evaluated on corpus luteum characteristics, reproductive tract vascularization, and serum progesterone concentration from ovulation until day 15 postovulation. Groups were: G1: (control) - no hCG; G2: 2500 IU of hCG to induce ovulation when a follicle greater than 35mm and uterine edema were detected; G3: 2500 IU hCG on day 0; G4: 2500 IU hCG on day 5 postovulation. Twelve mares were randomly assigned to each group, during consecutive cycles, in a Latin Square experimental design, in a total of 48 cycles. Doppler ultrasound evaluations were performed daily from day 0 until day 15 postovulation, including mesometrial vascularity, endometrial vascularity and corpus luteum vascularity. Blood samples were collected for serum progesterone concentration. Data was analyzed using the Proc Glimmix SAS Procedure for nonparametric variables and Proc Mixed for parametric parameters. There was no treatment effect for all variables studied (P > 0.05). Characteristics were only affected by day (P < 0.05). It can be concluded that hCG administration at the time points suggested in the current study did not alter the characteristics evaluated.

Morphological and molecular differences in corpus luteum of pregnant sows from divergent genetic groups

Comprehending mechanisms controlling corpus luteum (CL) angiogenesis and apoptosis in pregnant sows is essential to understand the physiological role of these processes in CL function, progesterone production and consequently in conceptus development and prenatal mortality. CL from 54 sows from two genetic groups, a commercial line (COM) and the local Piau breed (LPB), were obtained for gene expression (n = 3 COM; n = 6 LPB), histological and protein analysis (n = 3 COM; n = 3 LPB), divided in six gestational ages (seven, 15, 30, 45, 60 and 90 days). We observed differences between gestational ages in CL morphology, in which the average number of blood vessels/capillaries at 90-days was greater than at the seventh day by Tukey test. RT-qPCR analysis revealed that apoptotic genes (BAX, BCL2 and CASP3) were differentially expressed between genetic groups and gestational ages in each group. Angiogenesis genes also presented differences between genetic groups (ANGPT1) and gestational ages (MMP9, VEGFA and ANGPT1). No differences in protein abundance of steroidogenic enzymes (CYP11A1 and HSD3B1) were observed. Our findings indicate that despite the differences in gene expression, differences in corpus luteum vascularization were observed only across gestational ages, with no dissimilarities between genetic groups.

Corpus Luteum Vascularization and Progesterone Production in Autumn and Winter Cycles of the Mare: Relationship Between Ultrasonographic Characteristics of Corpora Lutea and Plasma Progesterone Concentration in the Last Cycles Before Anestrus

In 20 estrus cycles of 15 mares, Color Doppler ultrasound of corpora lutea and plasma progesterone concentration (P4) was analyzed on days 6, 10, 14, 16, and 18 after ovulation. Progesterone concentration was positively correlated with corpora lutea cross-sectional area (CSA), vascularized area (VA), and index of vascularization (IV = VA/CSA) (P < .0001). Cross-sectional area, VA, and IV in corpora lutea of mares with P4 < 1 ng/mL were significantly lower than in corpora lutea of mares with P4 > 1 ng/mL. Mares with CSA < 3,473 pixels, VA < 25.5 pixels, and IV < 7.6% were prone to express P4 < 1 ng/mL 25.4, 7.9, and 7.6 times more than mares with higher values, respectively. Corpus luteums analyzed parameters differed significantly between last cycles (LCs) of the breeding season and previous cycles until day 14 after ovulation (P < .05). No significant differences were found in P4 between LCs and previous ones.

Growth Arrest Specific-1 (GAS1) Is a C/EBP Target Gene That Functions in Ovulation and Corpus Luteum Formation in Mice.

Ovulation and luteinization are initiated in preovulatory follicles by the luteinizing hormone (LH) surge; however, the signaling events that mediate LH actions in these follicles remain incompletely defined. Two key transcription factors that are targets of LH surge are C/EBPalpha and C/EBPbeta, and their depletion in granulosa cells results in complete infertility. Microarray analyses of these mutant mice revealed altered expression of a number of genes, including growth arrest specific-1 (Gas1). To investigate functions of Gas1 in ovulation- and luteinization-related processes, we crossed Cyp19a1-Cre and Gas1flox/flox mice to conditionally delete Gas1 in granulosa and cumulus cells. While expression of Gas1 is dramatically increased in granulosa and cumulus cells around 12–16 h post-human chorionic gonadotropin (hCG) stimulation in wild-type mice, this increase is abolished in Cebpa/b double mutant and in Gas1 mutant mice. GAS1 is also dynamically expressed in stromal cells of the ovary independent of C/EBPalpha/beta. Female Gas1 mutant mice are fertile, exhibit enhanced rates of ovulation, increased fertility, and higher levels of Areg and Lhcgr mRNA in granulosa cells. The morphological appearance and vascularization of corpora lutea appeared normal in these mutant females. Interestingly, levels of mRNA for a number of genes (Cyp11a1, Star, Wnt4, Prlr, Cd52, and Sema3a) associated with luteinization are decreased in corpora lutea of Gas1 mutant mice as compared with controls at 24 h post-hCG; these differences were no longer detectable by 48 h post-hCG. The C/EBP target Gas1 is induced in granulosa cells and is associated with ovulation and luteinization.

Reducing the Risk of OHSS by GnRH Agonist Triggering

Overstimulation of follicle development in assisted reproductive technology cycles can lead to the development of life-threatening ovarian hyperstimulation syndrome (OHSS). There is evidence that administration of GnRH agonist as the trigger for final follicular maturation, instead of the usual human chorionic gonadotropin trigger, will reduce the risk of OHSS by shortening the duration of luteal stimulation, lowering estrogen levels by inducing luteolysis and reducing the secretion of vascular endothelial growth factor (VEGF). The paper by Miller et al (1) in this month's issue of the Journal of Clinical Endocrinology and Metabolism (JCEM) demonstrates that GnRH agonist may directly reduce the activity of VEGF by stimulation of granulosa cell expression and secretion of pigment epithelial-derived factor (PEDF). The increased expression and secretion of PEDF in response to a bolus of GnRH agonist may antagonize the adverse effects of VEGF on ovarian vascular permeability and may contribute to luteolysis by reducing corpus luteum vascularity, thereby reducing the risk of OHSS. In addition, stimulation of PEDF may also be part of the protective mechanism of dopamine agonists used for prevention of OHSS. The new data presented by Miller et al (1) propose a likely mechanism for the reduced risk of OHSS following GnRH agonist triggering of follicle maturation in assisted reproductive technology cycles.

3D power Doppler ultrasound characteristics of the corpus luteum and early pregnancy outcome

Abstract Objective: to assess the relationship of corpus luteum morphology and vascularity by 3 dimensional power Doppler ultrasound and the pregnancy outcome in early pregnancy. Design: prospective observational cohort study. Setting: Zagazig University Hospital. Materials and methods: this is a prospective observational cohort study of thirty six pregnant patients examined by two dimensional and three dimensional transvaginal sonography for corpus luteum volume, echostructure and corpus luteum vascularization index in the period after documentation of fetal heart activity and nine weeks. Results: there were 36 study women, ultrasound morphologic features of corpus luteum: volume ranged from 0.91 to 42.8 ml with median of 6.85, vascularization index ranged from 0.05 to 23.8 with a median of 6.85, echostructure was cystic in 12 women (33.3%), hemorrhagic in 18 (50%) and solid in 6 women (16.7%). The relation between CL volume and pregnancy outcome was significant ( p -value was 0.02), being smaller in group of missed abortion. The relation between CL VI and pregnancy outcome was non significant ( p -value was 0.229). The relation between CL echostructure and pregnancy outcome was highly significant ( p -value was 0.009). The prognosis was worst in group of solid echostructure. Conclusion: the corpus luteum volume and echostructure assessed by 3D power Doppler ultrasound have statistical relationship with the early pregnancy outcome.

Fertility in a high-altitude environment is compromised by luteal dysfunction: the relative roles of hypoxia and oxidative stress

BackgroundAt high altitudes, hypoxia, oxidative stress or both compromise sheep fertility. In the present work, we tested the relative effect of short- or long-term exposure to high altitude hypobaric hypoxia and oxidative stress on corpora luteal structure and function.MethodsThe growth dynamics of the corpora lutea during the estrous cycle were studied daily by ultrasonography in cycling sheep that were either native or naïve to high-altitude conditions and that were supplemented or not supplemented with antioxidant vitamins. Arterial and venous blood samples were simultaneously drawn for determination of gases and oxidative stress biomarkers and progesterone measurement. On day five after ovulation in the next cycle, the ovaries were removed for immunodetection of luteal HIF-1alpha and VEGF and IGF-I and to detect IGF-II gene expression.ResultsThe results showed that both short- and long-term exposure to high-altitude conditions decreased luteal growth and IGF-I and IGF-II gene expression but increased HIF-1 alpha and VEGF immunoexpression. The level of plasma progesterone was also increased at a high altitude, although an association with increased corpus luteum vascularization was only found in sheep native to a high-altitude location. Administration of antioxidant vitamins resulted in a limited effect, which was restricted to decreased expression of oxidative stress biomarkers and luteal HIF-1alpha and VEGF immunoexpression.ConclusionsExposure of the sheep to high-altitude hypobaric hypoxia for short or long time periods affects the development and function of the corpus luteum. Moreover, the observed association of oxidative stress with hypoxia and the absence of any significant effect of antioxidant vitamins on most anatomical and functional corpus luteum traits suggests that the effects of high altitude on this ovarian structure are mainly mediated by hypoxia. Thus, these findings may help explain the decrease in sheep fertility at a high altitude.

Mast cell dynamics in the house rat (Rattus rattus) ovary during estrus cycle, pregnancy and lactation.

The distribution of mast cells in various ovarian compartments was studied during different stages of the reproductive cycles in Rattus rattus. Two types of mast cell populations were recognized with light microscopy i.e., light purple and deep purple, the latter also includes deeply stained cells with extruded granules. Mast cells identified by electron microscopy showed the ultrastructural features during granule formation and release of their content. Significantly higher numbers of mast cells per unit area of ovary were seen at estrus and diestrus. Numbers of mast cells also remained high during pregnancy with possible involvement of mast cell products in vascularization of corpora lutea. A positive correlation existed between mast cell counts and embryo number during pregnancy. However, numbers of mast cells declined significantly after parturition.