Corpus Luteum Area Research Articles

Comparison between transrectal palpation, B-mode and Doppler ultrasonography to assess luteal function in Holstein cattle.

Over the years, the most common methods for monitoring reproductive health in cattle have varied from transrectal palpation to B-mode ultrasonography. Nowadays, some portable ultrasound equipment includes the Doppler mode. Therefore, the aim of this study was to compare the accuracy of the different methods to assess corpus luteum (CL) functionality. In Experiment 1, 53 Holstein lactating cows undergoing a synchronization protocol were examined via transrectal palpation and B-mode scanning. Measurements for the largest diameter (LAD) and subjective size of CL (SCLS) were collected. Data were analyzed using correlation analysis and ROC Curves. In Experiment 2, 30 Holstein non-lactating cows with a CL were administered PGF2α and examined several times after injection, first in B-mode and then with Power Doppler. Measurements for LAD, CL area (CLA) and subjective and objective CL blood flow were collected. Blood samples were taken in both experiments to determine P4 concentration. Data were analyzed using correlation analysis and the GLM repeated measures test. Results for Experiment 1 showed that LAD was more accurate than SCLS. In Experiment 2, CLA was the best measurement to assess CL function, although both subjective and objective CL blood flow offer accurate information 24 h after PGF2α administration. Consequently, ultrasonography provides more accurate information about CL function than transrectal palpation. Although CLA seems to be an earlier indicator of luteal function than blood flow, 24 h after the onset of luteolysis, both parameters are valid.

185 Effect of time of equine chorionic gonadotrophin administration in a fixed-time artificial insemination protocol on ovulation, and corpus luteum area and blood flow of 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

Seasonal variation of the estrous cycle length, corpus luteum area, and size of the pre-ovulatory follicle in Criollo Limonero heifers.

In order to determine whether seasonal variations may influence the estrous cycle length (ECL), corpus luteum size (CLS), maximum area of CL (MACL), day of cycle with maximum area of CL (DCMACL), and pre-ovulatory follicles size (PFS), ten Criollo Limonero heifers were subjected to daily ultrasound ovary scanning throughout their estrous cycles during three seasons: hot-dry (HD), hot-humid (HH), and wind-rain (WR). The effect of season on ECL, MACL, DCMACL, and PFS was analyzed with an ANOVA (PROC GLM, SAS), whereas, for the effect of season on CLS, an ANOVA with repeated measures (PROC MIXED, SAS) was used. Results showed no effect (P > 0.05) of season on ECL, MACL, and DCMACL. However, size of PFS was larger (P < 0.02) during the WR season and the CLS tended (P < 0.09) to be lower during the HH. In conclusion, the relative stability of ECL, MACL, DCMACL, PFS, and CLS measures suggests no major seasonal variations which could imply adaptation capability of Criollo Limonero cattle to the tropical environment.

Assessment of Age Effects on Ovarian Hemodynamics Using Doppler Ultrasound and Progesterone Concentrations in Cycling Spanish Purebred Mares.

Simple SummaryPower Doppler is a non-invasive imaging technique that allows complete monitoring of the ovary changes in cycling mares. We use Power Doppler to investigate differences in follicular diameter and corpus luteum area as well as in follicular and corpus luteum blood flows between young and mature Spanish Purebred mares. Young mares had higher follicular and corpus luteum blood flows as well as higher blood progesterone levels. Moreover, we found that blood progesterone levels could be predicted in both groups from corpus luteum blood flow with moderate precision and accuracy. These results support the usefulness of Power Doppler to monitor ovarian hemodynamics and the suitability of corpus luteum blood flow to estimate blood progesterone levels in cycling mares.In equine reproduction, accurate and timely detection of the moment of ovulation is of great importance. Power Doppler ultrasound technology is a non-invasive method that enables to assess the morpho-echogenic features and blood flow changes during the estral cycle in mares. The objective of the present study was to evaluate the influence of age on ultrasonographic parameters (follicular diameter, follicular blood flow—FBF, corpus luteum (CL) area and corpus luteum blood flow—CLBF) and blood plasma progesterone concentrations in cycling Spanish Purebred mares (15 less than 8 years old and 15 equal o higher than 8 years old). The ultrasound images obtained were analyzed with the Image Colour Summarizer software, which allows the quantification of the pixels of each image. Young mares had significantly higher FBF, CLBF and plasma progesterone levels. Moreover, linear regression analysis showed that blood progesterone levels could be predicted in both groups from CLBF with moderate precision and accuracy. In conclusion, Power Doppler was useful to assess ovarian hemodynamics. Our results support that age is a factor that significantly influences FBF and CLBF as well as blood progesterone concentration in mares. More studies would be needed to develop high precision and accuracy predictive models of blood progesterone concentration from CLBF measured by Power Doppler.

Parenteral Copper Administration at the Beginning of a Fixed-Time Artificial Insemination Protocol in Beef Cattle: Effect on Ovarian Function and Pregnancy Rates.

The aim of this study was to evaluate the association between plasma copper (Cu) concentration and ovarian function during a fixed-time artificial insemination (FTAI) protocol and the effect of parenteral Cu administration (100mg) at the start of such protocol (day 0) on area of preovulatory follicle (APF); area of corpus luteum (ACL), plasma estradiol (E2), and progesterone (P4) concentrations; CL blood flow (CLBF); and pregnancy rate in beef heifers and cows. In cows, plasma Cu concentration on days 0 and 7 correlated positively with APF. Copper administration increased plasma Cu concentration and decreased APF and plasma E2 concentration (day 9), without modifying ACL, plasma P4 concentration, and CLBF (day 16) in cows. Pregnancy rate was higher in Cu-supplemented cattle on day 41 after FTAI as compared with controls (58.76 and 45.28%, respectively). In conclusion, Cu administration at the beginning of the FTAI protocol increased pregnancy rate in beef heifers and cows, modifying APF and plasma E2 concentration in the latter.

Luteogenesis and Embryo Implantation Are Enhanced by Exogenous hCG in Goats Subjected to an Out-of-Season Fixed-Time Artificial Insemination Protocol.

Simple SummaryIn temperate and subtropical ecosystems, goats are classified as seasonal-polyestrous, generating a seasonality in their products (i.e., milk, meat). In order to abolish or reduce this reproductive seasonality, exogenous hormones, such as human chorionic gonadotropin (hCG), have been used to stimulate the development of ovarian follicles, triggering ovulation, corpus luteum formation, while increasing serum progesterone levels, fetal growth, prolificacy, and kidding rate. We tested the possible effect of two doses of hCG (i.e., 100 vs. 300 IU) in the improvement of the luteal function and embryo implantation in anovulatory goats subjected to an estrus induction protocol, and then, to a fixed-time artificial insemination protocol (FTAI). The highest values for fecundity rate, corpus luteum area, as well as embryonic efficiency index 1, were favored in goats treated with 300 IU hCG 14 days post-artificial fertilization. The embryonic efficiency and the index embryonic implantation efficiency were favored in goats treated with 300 IU hCG 7 and 14 days post-artificial insemination. This work contributes to explore the most suitable use of exogenous hormones that favor the out-of-season reproductive outcomes in goats and to boost the embryo implantation efficiency.The aim of this study was to evaluate the possible effect of two doses of hCG (100 and 300 IU) applied at two different times (7 and 14 d) after a fixed-time artificial insemination protocol (FTAI) upon some variables involved in the embryonic implantation rate in goats during the natural deep anestrous season (April, 25° north). The experimental units considered crossbred, multiparous, anovulatory goats (n = 69, Alpine, Saanen, Nubian x Criollo), with average body weight (43.6 ± 5.7 kg) and body condition score (1.86 ± 0.28 units) located in northern–semiarid Mexico (25° N, 103° W). Once the goat’s anestrus status was confirmed, goats were subjected to an estrus induction protocol. Upon estrus induction confirmation, goats (n = 61) were subjected to a FTAI procedure. Immediately after the FTAI, the goats were randomly distributed to five experimental groups: (1). G100-7 (n = 13) 100 IU, hCG 7 d post-FTAI, (2). G100-14 (n = 12) 100 IU hCG, 14 d post-FTAI, (3). G300-7 (n = 12) 300 IU, hCG, 7 d post-FTAI, (4). G300-14 (n = 12) 300 IU hCG 14 d post-FTAI, and (5). Control group, CONT (n = 12) 0.5 mL saline, 7 and 14 d post-FTAI. The response variables conception rate (39.36 ± 0.23), fertility rate (27.96%), prolificacy rate (1.1 ± 0.29 kids), ovulation rate (0.74 ± 0.20 corpus luteum) corpus luteum diameter (10.15 ± 0.59 mm), embryo number (1.58 ± 0.20), and embryo implantation rate (48.96%), did not differ between treatments. However, while the variables fecundity rate (67%), embryo efficiency index-1 (33.99 ± 0.20%), and embryo efficiency index-2 (27.94 ± 0.30%) were favored by the G300-14 treatment, the corpus luteum area was favored (p < 0.05) by both G300-7 (113.30 ± 0.19 mm2) and G300-14 (103.04 ± 0.17 mm2). Such reproductive strategy emerges as an interesting approach, not only to enhance the out-of-season reproductive outcomes, but also to boost one of the main rulers defining the global reproductive efficiency of a heard, namely, the embryo implantation efficiency.

Impact of slick hair trait on physiological and reproductive performance in beef heifers consuming ergot alkaloids from endophyte-infected tall fescue1.

Fescue toxicosis is a multifaceted syndrome common in cattle grazing endophyte-infected tall fescue. The objective of this study was to evaluate the impact of the slick hair trait on physiological and reproductive parameters in heifers experiencing fescue toxicosis. Angus × Senepol heifers (n = 31) were blocked by weight (393.5 ± 17.3 kg) and phenotype relative to hair coat at birth, and randomly fed novel endophyte fescue (EN) or endophyte-infected fescue (EI) haylage in a total mixed ration for 91 d. Weekly measurements were collected to monitor heifer growth and response during ergot alkaloids exposure. Following 28 d of treatment, estrus was synchronized and heifers were inseminated. Ovary mapping and AI pregnancy rate were examined via transrectal ultrasonography. Blood samples were taken for genotyping: slick (S) or wildtype (W). Data were analyzed using repeated measures in PROC MIXED of SAS including fescue treatment (EN vs. EI), genotype (S vs. W), and sample collection time as main effects. Body condition scores were decreased for W heifers compared with S heifers (5.48 vs. 5.66, respectively; P < 0.0001). Surface temperature was greater for EI-W heifers (37.2 °C) compared with other groups (36.4, 36.6, 36.7 °C for EN-S, EN-W, EI-S, respectively; P < 0.05). Serum PRL concentrations were reduced for EI heifers compared with EN heifers (133.5 vs. 163.1 ng/mL, respectively; P < 0.05). The average number of 2 to 4 mm follicles were greater in EI-W heifers (13.8 follicles) compared with other groups (12.2, 10.6, and 11.1 for EN-S, EN-W, and EI-S, respectively; P < 0.0001). However, the average number of preovulatory follicles (≥9 mm) were reduced in EI-W heifers (0.52 follicles) compared with other heifer groups (0.94, 0.88, and 0.85 ± 0.04 for EN-S, EN-W, and EI-S, respectively; P < 0.05). Ovulatory follicle size was smaller in EI-W heifers compared with EN-W heifers (9.14 vs. 11.57 mm, respectively; P = 0.05). Corpus luteum area was reduced in EI-W heifers (235.1 mm2) compared with other heifer groups (297.2, 272.7, and 276.8 mm2 for EN-S, EN-W, and EI-S, respectively; P < 0.05). Concentrations of P4 were greater for EN heifers compared with EI heifers (2.7 vs. 1.8 ng/mL, respectively; P < 0.05). Pregnancy was not established in EI-W heifers (0%) compared with other heifer groups (37.5%, 57.1%, and 62.5% for EN-S, EN-W, and EI-S, respectively; P < 0.05). Overall, the slick hair mutation appears to aid in offsetting the physiological symptoms associated with fescue toxicosis and helps to improve reproductive performance.

Ergot alkaloids induce vasoconstriction of bovine uterine and ovarian blood vessels.

Fescue toxicosis is a syndrome that impairs growth and reproduction in cattle grazing endophyte-infected tall fescue [Lolium arundinaceum [(Schreb.].) Darbysh)] in the United States, resulting in approximately $1 billion in annual economic loss in species that utilize this forage resource. Approximately 90% of tall fescue contains an endophytic fungus (Epichloë coenophiala) that produces ergot alkaloids. Ergot alkaloids cause vasoconstriction and reduced blood flow to the extremities; however, it remains unknown how blood flow to the reproductive organs is affected in cattle. Therefore, the objective of this study was to determine if ergot alkaloids from endophyte-infected tall fescue reduce blood flow to the reproductive organs, thus hindering reproductive function. Angus heifers (n = 36) naïve to ergot alkaloids were placed in Calan gates and randomly assigned to receive either endophyte-infected fescue seed (E+) or noninfected fescue seed (E-; control) in a total mixed ration for 63 d. Weekly measurements were taken to monitor heifer growth and response to ergot alkaloid exposure. Reproductive measurements, including ovarian structures, uterine and ovarian vessel diameter, and hormone concentrations were determined after heifers were synchronized using the standard CO-Synch + 7 d CIDR protocol to ensure all measurements were collected at the same stages of the estrous cycle (0, 4, 10, and 17 d). Data were analyzed using repeated measures in PROC MIXED of SAS. Average daily gain was decreased for the E+ group (0.8 kg/d) compared to control heifers (1.0 kg/d). Body condition scores tended to be greater in control heifers compared to the E+ group (P = 0.053). Additionally, hair coat and hair shedding scores were greater in E+ heifers compared to controls (P < 0.05). Heart rate, rectal temperature, respiration rate, and blood pressure did not differ between treatments (P > 0.05). Vasoconstriction was observed in the caudal artery, but not the caudal vein, in heifers consuming the E+ fescue seed (P < 0.05). No differences were observed in antral follicle counts, corpus luteum area or circulating progesterone concentrations in E+ heifers compared to controls (P > 0.05). There was a significant decrease in the diameter of arteries and veins servicing the ovary and uterus on day 10 and 17 of the estrous cycle. Reduction in blood flow to the reproductive organs during critical times in the estrous cycle may contribute to the reduced ovarian function and pregnancy rates associated with fescue toxicosis.

Equine chorionic gonadotropin administration after insemination affects luteal function and pregnancy establishment in postpartum anestrous beef cows

Two experiments were conducted with the aim of determining the effect of equine chorionic gonadotropin (eCG) administration on day 14 after insemination on ovarian response and pregnancy establishment in postpartum anestrous beef cows. In both experiments, cows were subjected to a progesterone- and estradiol-based treatment for fixed-time artificial insemination (FTAI) and were randomly allocated into 4 groups to receive or not receive eCG (400 IU) at the time of device removal and/or at 14 d after FTAI. In experiment 1, from day 14 to 22, daily ultrasonographic determinations were performed to monitor ovarian dynamics, and blood was collected to determine hormone concentrations in 60 cows. In experiment 2, confirmation of pregnancy was performed at 30 and 60 d after FTAI in 1,060 anestrous cows assigned to the same experimental design. Cows that received eCG on day 14 after FTAI showed increases in corpus luteum area (P < 0.01), follicle diameter (P < 0.05), serum progesterone concentrations (P < 0.01), and estradiol-17β concentrations (P < 0.01), compared with cows that did not receive eCG on day 14. Pregnancy rate on day 30 was greater in those cows that received both eCG treatments (ie, at device removal and 14 d after insemination) than in those that did not receive eCG treatment (P < 0.05). In conclusion, eCG administered on day 14 after FTAI increases serum progesterone concentrations during the critical period of pregnancy in anestrous cows, and this second eCG treatment seems to have a positive effect on achieving pregnancy.

Effect of injectable trace mineral complex supplementation on development of ovarian structures and serum copper and zinc concentrations in over-conditioned Holstein cows

This study evaluated the effect of injecting trace minerals on reproductive performance in over-conditioned Holstein cows before synchronized estrus. Multiparous non-lactating, over-conditioned repeat breeder cows (n=20) were assigned randomly to one of two treatments: 1) control (n=10), and 2) supplementation with an injectable trace mineral complex 25days before expected synchronized estrus (n=10). Follicular waves were synchronized by intravaginal insertion of a CIDR for eight days and an intramuscular (i.m.) injection of a GnRH analogue. Estrus was induced at CIDR removal by an i.m. injection of PGF2α. Blood samples were collected before and after synchronized estrus. The response variables were follicle population (FP), diameter of the preovulatory follicle at CIDR removal (DFP0) and at estrus detection (DFP1), time of estrus after CIDR removal (TE), area of corpus luteum (ACL), pregnancy rate and copper and zinc serum concentrations. The statistical analysis of the variables was carried out with SAS. The FP, DFP0, DFP1, TE, ACL and serum concentrations of copper and zinc were not affected by the trace mineral injection (P>0.05). Even though pregnancy rate at 40 (77.78±13.46 vs 44.44±16.56%) and 60days after AI (66.67±15.71 vs 33.33±15.71%) was numerically higher for cows injected with trace minerals than for the control group, the differences were not significant (P>0.05). In conclusion, while follicular and corpus luteum development were not affected by trace mineral injection, it may be a feasible way to increase the pregnancy rate in over-conditioned cows.

Whole flaxseed, raw soybeans, and calcium salts of fatty acids supplementation for transition cows: follicle development and embryo quality

The objective of this study was to evaluate the effects of diets rich in omega-3 and -6 fatty acids (FA) during the transition period and early lactation on size and number of follicles, oocyte and embryo quality, and blood metabolites of Holstein cows. Forty-two cows were assigned to the diets: control (CON, with no fat sources and dietary ether extract content of 28.8 and 24.8 g/kg during the pre- and post-partum periods, respectively); whole flaxseed (WF, diet rich in omega-3 FA), 60 and 80 g/kg of WF during the pre and post-partum periods, respectively; whole raw soybeans (WS, diet rich in omega-6 FA), 120 and 160 g/kg of WS during the pre and post-partum periods; and calcium salts of unsaturated fatty acids (CSFA, diet rich in omega-6 FA), 24 and 32 g/kg of CSFA during the pre and post-partum periods. Diets were supplied from 35 d of the expected calving date until 84 days in milk (DIM). The ovaries of cows were examined from 14 to 84 DIM. Ovum pick-ups were performed on days 35 ± 7 and 65 ± 7 of lactation. Diets rich in omega-3 and -6 FA had greater follicle number than the CON. No differences were detected among diets rich in omega-3 and omega-6 FA on number and size of follicles and corpus luteum area. Cows had similar oocyte quality regardless of diet supplied. Although FA supplementation had no effect on embryo quality (number of cleaved and viable embryos), diets rich in omega-6 FA had lower viable embryos compared with WF. Supplementation with diets rich in omega-3 and -6 FA resulted in greater blood cholesterol concentration in early lactation cows. Fat supplementation increased the number of small and total follicles of early lactating cows. However, diets rich in omega-3 or -6 FA had no effect on oocyte quality. Cows fed WS during the transition period had the least viable embryos, and consequently cows fed diets rich in omega-6 FA had lower viable embryos than those fed WF.

Establishment of critical timing of progesterone supplementation on corpus luteum and embryo development in beef heifers

Optimal concentrations of progesterone (P4) during early pregnancy are a major determinant of embryo survival in cattle. This study examined the effects of P4 supplementation, following a period of induced low P4, on corpus luteum (CL) development, circulating P4 concentrations and embryo development. A total of 107 beef heifers from one herd were used in the study. Following AI (Day 0) at a synchronized oestrus, heifers were randomly assigned to 1 of 5 treatment groups: (1) no subsequent treatment (control; n=15); (2) administration of a synthetic prostaglandin F2α analogue (PG) on Days 3, 3.5 and 4 to induce low P4 and no further treatment (LP4; n=23); administration of PG as above followed by P4 supplementation via insertion of a Controlled Internal Drug Release device from (3) Day 4–7 (P4 d4-7; n=22); (4) Day 4–10 (P4 d4-10; n=23); or (5) Day 7–10 (P4 d7-10; n=24). Embryo and CL characteristics were determined following slaughter on Day 16. Embryo size was greater in heifers administered P4 d4-7 and P4 d4-10 in comparison with LP4. Corpus luteum area was significantly reduced in heifers administered P4 d4-7 and P4 d4-10 up to Day 7, and Day 10 (P4 d4-10), in comparison with LP4 heifers. Initiation of supplemental P4 on Day 7 had no effect on CL area or embryo size in comparison with LP4 heifers. Concentrations of P4 were less in P4 d4-7, P4 d7-10 and P4 d4-10 on Day 15 in comparison with LP4 heifers. The results of the study indicate an initiation and duration effect of supplemental P4 on circulating P4, embryo and CL development following induction of LP4 on Day 3 and 4.

Corpus luteal angiogenesis in a high milk production dairy breed differs from that of cattle with lower milk production levels

Globally, high producing, young dairy cows often have health and fertility problems such as ovarian, uterine and placental dysfunction, mastitis and impaired wound healing. These health issues can result in a shortened average lifespan of fewer than three lactations. We hypothesise that many of these health issues may be an effect of altered angiogenesis. Hence, the aim of this pilot study was to investigate the status of vascularisation in the corpus luteum of a high milk-producing cattle breed (Holstein Friesian) compared with that of low milk producing beef cattle (Limousin) and of dual purpose cattle (Fleckvieh, Rotbunt). The corpus luteum was chosen because as a transient endocrine gland it is one of the few tissues with physiological angiogenesis in the adult. Blood vessels were labelled in paraffin sections of corpora lutea with the lectin Bandeiraea simplicifolia agglutinin I and the following angiogenesis parameters were analysed morphometrically using image analysis: (a) number of blood capillaries per mm&lt;sup&gt;2&lt;/sup&gt;, (b) intercapillary distance, (c) percentage area occupied by blood vessels and (d) area of blood vessel lumina (μm&lt;sup&gt;2&lt;/sup&gt;). This analysis revealed that the extent of corpus luteal vascularisation is greater in high milk-producing cattle than in beef and dual purpose cattle as shown by a significantly higher number of blood capillaries per mm², significantly shorter intercapillary distances and a higher percentage of the corpus luteum area covered by blood vessels (non-significant). Only the average value of the luminal area of the luteal blood capillaries in the high milk-producing cattle is smaller than that measured in the low producing cattle.

Luteal response and follicular dynamics induced with equine chorionic gonadotropin (eCG) administration after insemination in sheep

The objective of this study was to evaluate the ovarian response to equine chorionic gonadotropin (eCG) administrated during the luteal phase after insemination in sheep. Thirty cyclic multiparous ewes received a fixed-time intrauterine insemination (Day 0) and were assigned to three experimental groups that received 400 IU of eCG on Day 5 (n=10) or Day 10 (n=10), while another group remained as control group without eCG (n=10). Corpus luteum area and follicular diameter were daily measured by transrectal ultrasonography and serum progesterone concentrations were daily determined by radioimmunoassay during 30days after insemination in pregnant ewes or until the following ovulation in non pregnant ewes. The administration of eCG on Day 10, but not on Day 5, increased corpus luteum size and serum progesterone concentrations (P<0.05). Follicular dynamics were influenced by both eCG treatments on Day 5 and Day 10, promoting the growth of the largest follicle present during treatment or increasing the length of the wave that emerged after treatment (P<0.05). In conclusion, the administration of 400 IU of eCG 10 days after insemination in sheep increased corpus luteum size and progesterone concentrations, as well as promoted follicular development. This information could be useful to develop new pharmacological strategies to improve the establishment of pregnancy in sheep.

Assessment of seasonal variations in plasma progesterone concentrations and the morphometry of corpus luteum and ovary during estrous in Nili-Ravi buffalo

The influence of season on the plasma progesterone concentrations and morphometric values of corpus luteum and ovary was studied through ultrasonography in spring (n=10) and dry hot (n=10) seasons on alternate days during the estrous cycle regardless of estrous phases in Nili-Ravi buffaloes. The mean morphometric values of length and width of ovary and the diameter and area of corpus luteum were higher in spring than those in dry hot seasons. The plasma progesterone concentrations were determined by ELISA (Enzyme Linked Immuno Sorbent Assay) technique and influence of seasons was found significant (P

Copper/Zinc Superoxide Dismutase Insufficiency Impairs Progesterone Secretion and Fertility in Female Mice1

Copper/zinc superoxide dismutase (CuZn-SOD, SOD1) is one of the major antioxidant enzymes, and is localized in the cytoplasm to scavenge superoxide. To investigate the physiological role of SOD1 in the ovaries, we analyzed the fertility of Sod1-deficient female mice. To evaluate their hormonal metabolism, we measured pituitary and ovarian hormone levels in the plasma of the mutant mice. Plasma follicle-stimulating hormone, luteinizing hormone, and estradiol were not altered in the mutant compared to the wild-type females, while the plasma progesterone level was significantly reduced in the mutant females. Furthermore, the mutant mice showed decreased progesterone secretion under the condition of superovulation. In a histochemical analysis, we observed a remarkable reduction in the corpus luteum area in the mutant ovaries without atrophic changes. The mutant mice also displayed enhanced superoxide generation in the region surrounding the corpora lutea, which was associated with increased apoptotic cells and suppressed vasculature. These results suggested that SOD1 deficiency dysregulated luteal formation because of increased superoxide generation in the ovary. In vitro fertilization experiments showed no abnormal fertilization of Sod1-deficient oocytes. In addition, when Sod1-deficient embryos were transferred into the oviducts of wild-type females, mutant embryos developed at a normal rate, indicating that SOD1 deficiency in embryos did not cause miscarriage in the uterus of wild-type females. These results indicated that increased intracellular ROS impaired luteal formation and progesterone production in the mutant females, thus suggesting that SOD1 plays a crucial role in both the luteal function and the maintenance of fertility in female mice.

Concentrations of circulating hormones normalized to pulses of a prostaglandin F 2α metabolite during spontaneous luteolysis in mares

The temporal relationships between a pulse of 13,14-dihydro-15-keto-PGF 2α (PGFM) and the concentrations of circulating hormones during the luteolytic period were studied for 11 pulses in 11 mares (Equus caballus) using samples collected hourly. Mean PGFM pulses encompassed 4 h before to 4 h after the peak, and hormone data were normalized to the PGFM peak (Hour 0). Concentration of progesterone decreased (P < 0.05) between Hours –4 and –3 and continued to decrease linearly throughout the PGFM pulse. The concentrations of cortisol and prolactin increased (P < 0.004) during Hours –4 to 0 and decreased (P < 0.002) during Hours 0 to 4. Estradiol concentration increased (P < 0.02) during Hours –4 to 0 but did not change significantly after Hour 0. Concentrations of follicle-stimulating hormone and luteinizing hormone did not change significantly during the PGFM pulse, and the oxytocin results were equivocal. Percentage of corpus luteum area with color-Doppler signals of blood flow did not change significantly between Hours –4 and 0 and first began to decrease (P < 0.004) between Hours 0 and 2. Results demonstrated that concentrations of progesterone decreased linearly during a PGFM pulse, and cortisol, prolactin, and estradiol increased during the ascending portion of the pulse. The progesterone and gonadotropin results supported the hypothesis that the initial progesterone and gonadotropin increases that have been reported to occur in response to a single bolus luteolytic treatment with prostaglandin F 2α do not occur in response to the natural secretion of prostaglandin F 2α.

Ovarian histology and follicular score in female rats treated with nandrolone decanoate and submitted to physical effort

The study was conducted to analyze the histology of the ovaries of adults rats treated with steroids, and submitted or not to physical effort. The control group consisted of females submitted to physical effort and sedentary females, both of which received a physiological solution of 0.9% saline. Treated females, sedentary or not, received 6 mg/kg of body weight of nandrolone decanoate. The steroid and physiological solution were administered intraperitoneally, with a single injection per week for 4 consecutive weeks. The applied physical effort was swimming (20 minutes daily, 5 days/week, for the 4 weeks of treatment). Serial sections (5 mum) of ovaries were prepared for histological evaluation and follicular score. The weight of ovaries and hypophysis, the number of antral and atretic follicles, and the area of corpus luteum were all affected by the steroids. In the ovaries of the control groups, well-developed corpus luteum was observed. In the treated groups, the cortical stroma was occupied by ovarian interstitial tissue. The females treated with steroids presented estral acyclicity. The use of nandrolone decanoate, whether associated with physical effort or not, affected the morphological pattern of the ovaries.

Pregnancy rates and corpus luteum–related factors affecting pregnancy establishment in bovine recipients synchronized for fixed-time embryo transfer

The objective was to investigate the influence of corpora lutea physical and functional characteristics on pregnancy rates in bovine recipients synchronized for fixed-time embryo transfer (FTET). Crossbred ( Bos taurus taurus × Bos taurus indicus ) nonlactating cows and heifers (n = 259) were treated with the following protocol: 2 mg estradiol benzoate (EB) plus an intravaginal progesterone device (CIDR 1.9 g progesterone; Day 0); 400 IU equine chorionic gonadotropin (eCG; Day 5); prostaglandin F 2α (PGF 2α) and CIDR withdrawal (Day 8); and 1 mg EB (Day 9). Ovarian ultrasonography and blood sample collections were performed on Day 17. Of the 259 cattle initially treated, 197 (76.1%) were suitable recipients; they received a single, fresh, quality grade 1 or 2 in vivo –derived (n = 90) or in vitro–produced (n = 87) embryo on Day 17. Pregnancy rates (23 d after embryo transfer) were higher for in vivo –derived embryos than for in vitro–produced embryos (58.8% vs. 31.0%, respectively; P < 0.001). Mean (±SD) plasma progesterone (P 4) concentration was higher in cattle that became pregnant than that in nonpregnant cattle (5.2 ± 5.0 vs. 3.8 ± 2.4 ng/mL; P = 0.02). Mean pixel values (71.8 ± 1.3 vs. 71.2 ± 1.1) and pixel heterogeneity (14.8 ± 0.3 vs. 14.5 ± 0.5) were similar between pregnant and nonpregnant recipients (P > 0.10). No significant relationship was detected between pregnancy outcome and plasma P 4, corpus luteum area, or corpus luteum echotexture. Embryo type, however, affected the odds of pregnancy. In conclusion, corpus luteum–related traits were poor predictors of pregnancy in recipients. The type of embryo, however, was a major factor affecting pregnancy outcome.

Is slow follicular growth the cause of silent estrus in water buffaloes?

The present experiment was conducted to study the growth profile of the ovulatory follicle in relation to the expression of estrus following administration of PGF 2α to subestrus buffaloes. After detection of a mature corpus luteum by examination per rectum, confirmed by ultrasound scanning, subestrus buffaloes ( n = 20) were treated (Day 0) with single dose of Dinoprost tromethamin (25 mg, i.m.). Blood samples were collected at 0, 24 and 48 h after treatment for estimation of plasma progesterone concentration. Growth profile of the ovulatory follicle was monitored daily through ultrasound scanning starting from Day 0 until ovulation and the regression profile of CL was monitored at 0, 24 and 48 h of treatment. Estrus was detected by exposure to a fertile buffalo bull three times a day until expression of overt estrus or ovulation. Behavioral estrus was recorded in 14 animals and 6 animals ovulated silently. Sixteen animals including six animals with silent estrus ovulated from the dominant follicle present at treatment (Group A) and remaining four animals ovulated from the dominant follicle of succeeding follicular wave (Group B). The intervals from treatment to estrus (6.5 ± 0.25 versus 3.2 ± 0.27 days, P < 0.001) and treatment to ovulation (7.5 ± 0.25 versus 5.4 ± 0.46 days, P < 0.005) were significantly longer in animals of Group B compared with animals of Group A. Significant differences were observed in growth profile of the ovulatory follicle between animals of Groups A and B with respect to size of the follicle on Day 0 (9.8 ± 0.7 versus 5.3 ± 0.45 mm, P < 0.001), daily growth rate (0.97 ± 0.07 versus 1.6 ± 0.2 mm/day, P < 0.01) and increase in diameter (4.1 ± 0.6 versus 7.8 ± 0.7 mm, P < 0.01). The animals with silent estrus (subgroup A-2) had significantly smaller diameter of the ovulatory follicle on Day 0 (7.7 ± 0.4 versus 11.0 ± 0.7 mm, P < 0.005), its daily growth rate was significantly slower (0.7 ± 0.02 versus 1.1 ± 0.1 mm/day, P < 0.01) and they recorded significantly longer interval from treatment to ovulation (7.3 ± 0.56 versus 4.2 ± 0.27 days, P < 0.001) compared with the animals that showed overt estrus (subgroup A-1). The corpus luteum area (CL area) and plasma progesterone (P 4) concentration declined continuously from 0 to 48 h after PGF 2α treatment in the animals of both the Groups A and B. Non-significant differences were observed in mean CL area and plasma P 4 concentration at 0, 24 and 48 h post-treatment between animals of Groups A and B and also between animals of subgroups A-1 and A-2. The small size and the slow growth rate of the ovulatory follicle were identified as the possible cause of silent estrus in subestrus buffaloes after PGF 2α treatment.