Effect of insulin-like growth factor system on luteinising angiogenesis.

Preovulatory follicle growth and the luteal transition requires intense angiogenesis. This enables progesterone production to increase sufficiently to support a pregnancy. Inadequate follicular or luteal vascularisation can lead to reduced ovarian function and thus compromise fertility. Insulin-like growth factor 1 (IGF1) and IGF2 regulate multiple ovarian processes and are key links between an animal's reproductive and metabolic status. This study investigated the role that the IGF system plays in regulating luteinising follicular endothelial cell (EC) networks and progesterone production in vitro. Bovine luteinising follicular angiogenesis cultures were treated with 1) LR3-IGF1 (10 or 100ng/ml) under basal and angiogenic-stimulated conditions or 2) IGF1 receptor inhibitor (picropodophyllin (PPP); 1µM) in the presence or absence of LR3-IGF1, IGF2, or combined LR3-IGF1+IGF2 (10ng/ml). EC networks were quantified by von Willebrand factor immunohistochemistry. Progesterone production was analysed by ELISA and cell proliferation was determined by MTT assay. LR3-IGF1 had limited effects on EC growth parameters, whilst PPP (p<0.001) markedly reduced EC growth parameters (by 60-70%). Cell proliferation was slightly increased (by 3-5%) by LR3-IGF1 (p<0.001). LR3-IGF1 had variable effects on progesterone production, whilst PPP reduced progesterone concentration (p<0.001) with or without LR3-IGF1 or IGF2 alone or in combination. IGF1 was detected in cell conditioned media and was increased by LH (50ng/ml) (p<0.001). In conclusion, exogenous IGF1 and IGF2 had minimal effects on luteinising follicular angiogenesis and progesterone production, but the inhibitory effect of the IGFR1 inhibitor (PPP) suggests that IGF1 receptor signalling is critical for the development of EC networks and progesterone production in luteinising follicular cells.

A randomised controlled trial to evaluate the impact of indoor living space on dairy cow production, reproduction and behaviour.

As a global society, we have a duty to provide suitable care and conditions for farmed livestock to protect animal welfare and ensure the sustainability of our food supply. The suitability and biological impacts of housing conditions for intensively farmed animals is a complex and emotive subject, yet poorly researched, meaning quantitative evidence to inform policy and legislation is lacking. Most dairy cows globally are housed for some duration during the year, largely when climatic conditions are unfavourable. However, the impact on biology, productivity and welfare of even the most basic housing requirement, the quantity of living space, remains unknown. We conducted a long-term (1-year), randomised controlled trial (CONSORT 10 guidelines) to investigate the impact of increased living space (6.5 m2 vs 3 m2 per animal) on critical aspects of cow biology, behaviour and productivity. Adult Holstein dairy cows (n = 150) were continuously and randomly allocated to a high or control living space group with all other aspects of housing remaining identical between groups. Compared to cows in the control living space group, cows with increased space produced more milk per 305d lactation (primiparous: 12,235 L vs 11,592 L, P < 0.01; multiparous: 14,746 L vs 14,644 L, P < 0.01) but took longer to become pregnant after calving (primiparous: 155 d vs 83 d, P = 0.025; multiparous: 133 d vs 109 d). In terms of behaviour, cows with more living space spent significantly more time in lying areas (65 min/d difference; high space group: 12.43 h/day, 95% CI = 11.70-13.29; control space group: 11.42 h/day, 95% CI = 10.73-12.12) and significantly less time in passageways (64 min/d), suggesting enhanced welfare when more space was provided. A key physiological difference between groups was that cows with more space spent longer ruminating each day. This is the first long term study in dairy cows to demonstrate that increased living space results in meaningful benefits in terms of productivity and behaviour and suggests that the interplay between farmed animals and their housed environment plays an important role in the concepts of welfare and sustainability of dairy farming.

Maternal protein restriction affects fetal ovary development in sheep.

Maternal malnutrition has important developmental consequences for the foetus. Indeed, adverse fetal ovarian development could have lifelong impact, with potentially reduced ovarian reserve and fertility of the offspring. This study investigated the effect of maternal protein restriction on germ cell and blood vessel development in the fetal sheep ovary. Ewes were fed control (n = 7) or low protein (n = 8) diets (17.0 g vs 8.7 g crude protein/MJ metabolizable energy) from conception to day 65 of gestation (gd65). On gd65, fetal ovaries were subjected to histological and immunohistochemical analysis to quantify germ cells (OCT4, VASA, DAZL), proliferation (Ki67), apoptosis (caspase 3) and vascularisation (CD31). Protein restriction reduced the fetal ovary weight (P < 0.05) but had no effect on fetal weight (P > 0.05). The density of germ cells was unaffected by maternal diet (P > 0.05). In the ovarian cortex, OCT4+ve cells were more abundant than DAZL+ve (P < 0.001) and VASA+ve cells (P < 0.001). The numbers, density and estimated total weight of OCT4, DAZL, and VASA+ve cells within the ovigerous cords were similar in both dietary groups (P > 0.05). Similarly, maternal protein restriction had no effect on germ cell proliferation or apoptotic indices (P > 0.05) and the number, area and perimeter of medullary blood vessels and degree of microvascularisation in the cortex (P > 0.05). In conclusion, maternal protein restriction decreased ovarian weight despite not affecting germ cell developmental progress, proliferation, apoptosis, or ovarian vascularity. This suggests that reduced maternal protein has the potential to regulate ovarian development in the offspring. LAY SUMMARY: Variations in a mother's diet during pregnancy can influence her offspring's growth and might cause fertility problems in the offspring in later life. We investigated whether reducing the protein fed to sheep during early pregnancy affects their daughters' ovaries. We then compared our findings to the offspring of sheep on a complete diet. We measured ovary size and estimated the number of germ cells (cells that become eggs) they contained. We used cell markers to assess potential changes in the pattern of germ cell growth, division, and death, and how the ovarian blood supply had developed. We found that protein restriction reduced ovary size. However, the pattern of germ cell development, growth, or death was not altered by poor diet and blood vessels were also unaffected. This suggests that maternal diet can change ovarian development by an unknown mechanism and might reduce future fertility in their offspring.

Transforming growth factor-ß1 disrupts angiogenesis during the follicular-luteal transition through the Smad-serpin family E member 1 (SERPINE1)/serpin family B member 5 (SERPINB5) signalling pathway in the cow.

Intense angiogenesis is critical for the development of the corpus luteum and is tightly regulated by numerous factors. However, the exact role transforming growth factor-ß1 (TGFB1) plays during this follicular-luteal transition remains unclear. This study hypothesised that TGFB1, acting through TGFB receptor 1 (TGFBR1) and Smad2/3 signalling, would suppress angiogenesis during the follicular-luteal transition. Using a serum-free luteinising follicular angiogenesis culture system, TGFB1 (1 and 10ngmL-1 ) markedly disrupted the formation of capillary-like structures, reducing the endothelial cell network area and the number of branch points (P <0.001 compared with control). Furthermore, TGFB1 activated canonical Smad signalling and inhibited endothelial nitric oxide synthase (NOS3 ) mRNA expression, but upregulated latent TGFB-binding protein and TGFBR1 , serpin family E member 1 (SERPINE1 ) and serpin family B member 5 (SERPINB5 ) mRNA expression. SB431542, a TGFBR1 inhibitor, reversed the TGFB1-induced upregulation of SERPINE1 and SERPINB5 . In addition, TGFB1 reduced progesterone synthesis by decreasing the expression of steroidogenic acute regulatory protein (STAR ), cytochrome P450 family 11 subfamily A member 1 (CYP11A1 ) and 3ß-hydroxysteroid dehydrogenase (HSD3B1 ) expression. These results show that TGFB1 regulates NOS3 , SERPINE1 and SERPINB5 expression via TGFBR1 and Smad2/3 signalling and this could be the mechanism by which TGFB1 suppresses endothelial networks. Thereby, TGFB1 may provide critical homeostatic control of angiogenesis during the follicular-luteal transition. The findings of this study reveal the molecular mechanisms underlying the actions of TGFB1 in early luteinisation, which may lead to novel therapeutic strategies to reverse luteal inadequacy.

Characterisation of Listeria monocytogenes isolates from cattle using a bovine caruncular epithelial cell model.

Listeria monocytogenes is an important foodborne pathogen in human and veterinary health, causing significant morbidity and mortality including abortion. It has a particular tropism for the gravid uterus, however, the route of infection in reproductive tissues of ruminants (i.e. placentome), is much less clear. In this study, we aimed to investigate a bovine caruncular epithelial cell (BCEC) line as a model for L. monocytogenes infection of the bovine reproductive tract. The BCEC infection model was used to assess the ability of 14 different L. monocytogenes isolates to infect these cells. Lysozyme sensitivity and bacterial survival in 580 µg lysozyme/ml correlated with attenuated ability to proliferate in BCEC (p = 0.004 and p = 0.02, respectively). Four isolates were significantly attenuated compared to the control strain 10403S. One of these strains (AR008) showed evidence of compromised cell wall leading to increased sensitivity to ß-lactam antibiotics, and another (7644) had compromised cell membrane integrity leading to increased sensitivity to cationic peptides. Whole genome sequencing followed by Multi Locus Sequence Type analysis identified that five invasive isolates had the same sequence type, ST59, despite originating from three different clinical conditions. Virulence gene analysis showed that the attenuated isolate LM4 was lacking two virulence genes (uhpT, virR) known to be involved in intracellular growth and virulence. In conclusion, the BCEC model was able to differentiate between the infective potential of different isolates. Moreover, resistance to lysozyme correlated with the ability to invade and replicate within BCEC, suggesting co-selection for surviving challenging environments as the abomasum.

Detrimental effects of uterine disease and lipopolysaccharide on luteal angiogenesis.

Reproductive tract inflammatory disease (RTID) commonly occurs after the traumatic events of parturition and adversely affects follicular function. This study is the first to describe the cellular and steroidogenic characteristics of corpora lutea from cattle with RTID and the effects of pathogen-associated molecular patterns (PAMPs) on luteal angiogenesis and function in vitro. Luteal weight (P < 0.05) and progesterone content (P < 0.05) were reduced (1.2-fold) in cows with RTID, accompanied by reduced CYP11A (P < 0.05), HSD3B (P < 0.01) and STAR (P < 0.01) protein expression. Immunohistochemistry revealed that luteal vascularity (VWF) and pericyte (ACTA2) coverage were >3-fold lower in RTID cows (P < 0.05). To link these observations to bacterial infection and determine specificity of action, a physiologically relevant luteal angiogenesis culture system examined the effects of PAMPs on endothelial cell (EC) network formation and progesterone production, in the presence of pro-angiogenic factors. Luteal EC networks were reduced ≤95% (P < 0.05) by lipopolysaccharide (LPS, toll-like receptor (TLR) 4 agonist) but not by TLR2 agonists lipoteichoic acid or peptidoglycan. Conversely, progesterone production and steroidogenic protein expression were unaffected by PAMPs (P > 0.05). Moreover, the adverse effect of LPS on luteal EC networks was dose-dependent and effective from 1 ng/mL (P < 0.05), while few EC networks were present above 10 ng/mL LPS (P < 0.001). LPS reduced proliferation (P < 0.05) and increased apoptosis of EC (P < 0.001). The specific TLR4 inhibitor TAK242 reversed the effects of LPS on EC networks. In conclusion, luteal vasculature is adversely sensitive to LPS acting via TLR4, therefore ovarian exposure to LPS from any Gram-negative bacterial infection will profoundly influence subsequent reproductive potential.

Vaccination of foals with a modified live, equid herpesvirus-1 gM deletion mutant (RacHΔgM) confers partial protection against infection.

Equid herpesvirus-1 (EHV-1) causes respiratory and neurological disease and late gestation abortion in pregnant mares. Current vaccines contain either inactivated or live EHV-1, but fail to provide complete clinical or virological protection, namely prevention of nasopharyngeal shedding and cell-associated viraemia. Thus, the development of novel products, such as modified live virus (MLV) vaccines which stimulate virus-specific, humoral and cell mediated immune responses more effectively remains a priority. Two groups of weaned foals (n = 6 each group) were used in a longitudinal, prospective, experimental study to evaluate immune responses elicited by two vaccinations with a glycoprotein M (gM) deletion mutant of EHV-1 (RacHdeltagM). Following two concurrent intranasal and intramuscular inoculations six weeks apart, vaccinated (8.4 ±â€¯0.2 months old) and control foals (6.2 ±â€¯0.4 months) were challenge infected intranasally with EHV-1 Ab4/8 four weeks after the second vaccination and clinical signs and virological replication measured. Vaccination caused no adverse events, but did stimulate significantly higher complement fixing and virus neutralizing antibodies in serum compared with control foals at either equivalent or pre-vaccination time points. Virus-specific nasopharyngeal antibody levels and cytotoxic T lymphocyte responses were not significantly different between the groups. Following challenge infection, these immune responses were associated with a reduction in clinical signs and virological replication in the vaccinated foals, including a reduction in duration and magnitude of pyrexia, nasopharyngeal shedding and cell-associated viraemia. We conclude that the RacHΔgM MLV primed EHV-1-specific humoral immune responses in weaned foals. However, complete virological protection by vaccination against EHV-1 requires further research.

Evaluation of progestogen supplementation for luteal phase support in fresh in vitro fertilization cycles.

OBJECTIVE: To evaluate the effectiveness of progestogen supplementation in improving clinical pregnancy rates in women undergoing fresh IVF cycles and to compare different routes, start times, durations, and estrogen coadministration regimen. DESIGN: Comprehensive systematic review and meta-analysis. SETTING: University. PATIENT(S): Women undergoing fresh IVF cycles who did and did not receive progestogen supplementation. INTERVENTION(S): Summary odds ratios (ORs) were calculated by binomial logistic regression. MAIN OUTCOME MEASURE(S): Clinical pregnancy rates. RESULT(S): Eighty-two articles (26,726 women) were included. Clinical pregnancy rates were increased by IM (OR = 4.57), vaginal (OR = 3.34), SC (OR = 3.36), or oral (OR = 2.57) progestogen supplementation versus no treatment. The greatest benefit was observed when progestogens were supplemented IM versus vaginally (OR = 1.37). The optimal time to commence administration was between oocyte retrieval and ET (OR = 1.31), with oocyte retrieval +1 day being most beneficial. Coadministration of estrogen had no benefit (OR = 1.33), whether progestogens were coadministered vaginally or IM. Clinical pregnancy rates were equivalent when progestogen supplementation was ceased after ≤3 weeks or continued for up to 12 weeks (OR = 1.06). CONCLUSION(S): This broad-ranging meta-analysis highlights the need to reevaluate current clinical practice. The use of progestogens in fresh IVF cycles is substantially beneficial to clinical pregnancy. Critically, the use of IM progestogens should not be dismissed, as it yielded the greatest clinical pregnancy rates. Pregnancy success was impacted by initiation of therapy, with 1 day after oocyte retrieval being optimal. There is little evidence to support coadministration of estrogen or prolonging progestogen treatment beyond 3 weeks.

Androgen dependent mechanisms of pro-angiogenic networks in placental and tumor development.

The placenta and tumors share important characteristics, including a requirement to establish effective angiogenesis. In the case of the placenta, optimal angiogenesis is required to sustain the blood flow required to maintain a successful pregnancy, whereas in tumors establishing new blood supplies is considered a key step in supporting metastases. Therefore the development of novel angiogenesis inhibitors has been an area of active research in oncology. A subset of the molecular processes regulating angiogenesis are well understood in the context of both early placentation and tumorigenesis. In this review we focus on the well-established role of androgen regulation of angiogenesis in cancer and relate these mechanisms to placental angiogenesis. The physiological actions of androgens are mediated by the androgen receptor (AR), a ligand dependent transcription factor. Androgens and the AR are essential for normal male embryonic development, puberty and lifelong health. Defects in androgen signalling are associated with a diverse range of clinical disorders in men and women including disorders of sex development (DSD), polycystic ovary syndrome in women and many cancers. We summarize the diverse molecular mechanisms of androgen regulation of angiogenesis and infer the potential significance of these pathways to normal and pathogenic placental function. Finally, we offer potential research applications of androgen-targeting molecules developed to treat cancer as investigative tools to help further delineate the role of androgen signalling in placental function and maternal and offspring health in animal models.

Luteal angiogenesis and its control.

Angiogenesis, the formation of new blood vessels from preexisting ones, is critical to luteal structure and function. In addition, it is a complex and tightly regulated process. Not only does rapid and extensive angiogenesis occur to provide the corpus luteum with an unusually high blood flow and support its high metabolic rate, but in the absence of pregnancy, the luteal vasculature must rapidly regress to enable the next cycle of ovarian activity. This review describes a number of key endogenous stimulatory and inhibitory factors, which act in a delicate balance to regulate luteal angiogenesis and ultimately luteal function. In vitro luteal angiogenesis cultures have demonstrated critical roles for fibroblast growth factor 2 (FGF2) in endothelial cell proliferation and sprouting, although other factors such as vascular endothelial growth factor A (VEGFA) and platelet-derived growth factor were important modulators in the control of luteal angiogenesis. Post-transcriptional regulation by small non-coding microRNAs is also likely to play a central role in the regulation of luteal angiogenesis. Appropriate luteal angiogenesis requires the coordinated activity of numerous factors expressed by several cell types at different times, and this review will also describe the role of perivascular pericytes and the importance of vascular maturation and stability. It is hoped that a better understanding of the critical processes underlying the transition from follicle to corpus luteum and subsequent luteal development will benefit the management of luteal function in the future.

Mathematical analysis of a model for the growth of the bovine corpus luteum.

The corpus luteum (CL) is an ovarian tissue that grows in the wound space created by follicular rupture. It produces the progesterone needed in the uterus to maintain pregnancy. Rapid growth of the CL and progesterone transport to the uterus require angiogenesis, the creation of new blood vessels from pre-existing ones, a process which is regulated by proteins that include fibroblast growth factor 2 (FGF2). In this paper we develop a system of time-dependent ordinary differential equations to model CL growth. The dependent variables represent FGF2, endothelial cells (ECs), luteal cells, and stromal cells (like pericytes), by assuming that the CL volume is a continuum of the three cell types. We assume that if the CL volume exceeds that of the ovulated follicle, then growth is inhibited. This threshold volume partitions the system dynamics into two regimes, so that the model may be classified as a Filippov (piecewise smooth) system. We show that normal CL growth requires an appropriate balance between the growth rates of luteal and stromal cells. We investigate how angiogenesis influences CL growth by considering how the system dynamics depend on the dimensionless EC proliferation rate, ρ5. We find that weak (low ρ5) or strong (high ρ5) angiogenesis leads to 'pathological' CL growth, since the loss of CL constituents compromises progesterone production or delivery. However, for intermediate values of ρ5, normal CL growth is predicted. The implications of these results for cow fertility are also discussed. For example, inadequate angiogenesis has been linked to infertility in dairy cows.

Fibroblast growth factor 2 induces the precocious development of endothelial cell networks in bovine luteinising follicular cells.

The transition from follicle to corpus luteum represents a period of intense angiogenesis; however, the exact roles of angiogenic factors during this time remain to be elucidated. Thus, the roles of vascular endothelial growth factor (VEGF) A, fibroblast growth factor (FGF) 2 and LH in controlling angiogenesis were examined in the present study. A novel serum-free luteinising follicular angiogenesis culture system was developed in which progesterone production increased during the first 5 days and was increased by LH (P<0.01). Blockade of signalling from FGF receptors (SU5402; P<0.001) and, to a lesser extent, VEGF receptors (SU1498; P<0.001) decreased the development of endothelial cell (EC) networks. Conversely, FGF2 dose-dependently (P<0.001) induced the precocious transition of undeveloped EC islands into branched networks associated with a twofold increase in the number of branch points (P<0.001). In contrast, VEGFA had no effect on the area of EC networks or the number of branch points. LH had no effect on the area of EC networks, but it marginally increased the number of branch points (P<0.05) and FGF2 production (P<0.001). Surprisingly, progesterone production was decreased by FGF2 (P<0.01) but only on Day 5 of culture. Progesterone production was increased by SU5402 (P<0.001) and decreased by SU1498 (P<0.001). These results demonstrate that FGF and VEGF receptors play a fundamental role in the formation of luteal EC networks in vitro, which includes a novel role for FGF2 in induction of EC sprouting.

The expression, regulation and function of secreted protein, acidic, cysteine-rich in the follicle-luteal transition.

The role of the tissue remodelling protein, secreted protein, acidic, cysteine-rich (SPARC), in key processes (e.g. cell reorganisation and angiogenesis) that occur during the follicle-luteal transition is unknown. Hence, we investigated the regulation of SPARC in luteinsing follicular cells and potential roles of SPARC peptide 2.3 in a physiologically relevant luteal angiogenesis culture system. SPARC protein was detected mainly in the theca layer of bovine pre-ovulatory follicles, but its expression was considerably greater in the corpus haemorrhagicum. Similarly, SPARC protein (western blotting) was up-regulated in luteinising granulosa but not in theca cells during a 6-day culture period. Potential regulatory candidates were investigated in luteinising granulosa cells: LH did not affect SPARC (P>0.05); transforming growth factor (TGF) B1 (P<0.001) dose dependently induced the precocious expression of SPARC and increased final levels: this effect was blocked (P<0.001) by SB505124 (TGFB receptor 1 inhibitor). Additionally, fibronectin, which is deposited during luteal development, increased SPARC (P<0.01). In luteal cells, fibroblast growth factor 2 decreased SPARC (P<0.001) during the first 5 days of culture, while vascular endothelial growth factor A increased its expression (P<0.001). Functionally, KGHK peptide, a SPARC proteolytic fragment, stimulated the formation of endothelial cell networks in a luteal cell culture system (P<0.05) and increased progesterone production (P<0.05). Collectively, these findings indicate that SPARC is intricately regulated by pro-angiogenic and other growth factors together with components of the extracellular matrix during the follicle-luteal transition. Thus, it is possible that SPARC plays an important modulatory role in regulating angiogenesis and progesterone production during luteal development.

Fibroblast growth factor 2 is a key determinant of vascular sprouting during bovine luteal angiogenesis.

Fibroblast growth factor (FGF) 2 and vascular endothelial growth factor (VEGF) A are thought to be key controllers of luteal angiogenesis; however, their precise roles in the regulation and coordination of this complex process remain unknown. Thus, the temporal and spatial patterns of endothelial network formation were determined by culturing mixed cell types from early bovine corpora lutea on fibronectin in the presence of FGF2 and VEGFA (6 h to 9 days). Endothelial cells, as determined by von Willebrand factor immunohistochemistry, initially grew in cell islands (days 0-3), before undergoing a period of vascular sprouting to display a more tubule-like appearance (days 3-6), and after 9 days in culture had formed extensive intricate networks. Mixed populations of luteal cells were treated with SU1498 (VEGF receptor 2 inhibitor) or SU5402 (FGF receptor 1 inhibitor) or control on days 0-3, 3-6 or 6-9 to determine the role of FGF2 and VEGFA during these specific windows. The total area of endothelial cells was unaffected by SU1498 treatment during any window. In contrast, SU5402 treatment caused maximal reduction in the total area of endothelial cell networks on days 3-6 vs controls (mean reduction 81%; P<0.001) during the period of tubule initiation. Moreover, SU5402 treatment on days 3-6 dramatically reduced the total number of branch points (P<0.001) and degree of branching per endothelial cell island (P<0.05) in the absence of changes in mean island area. This suggests that FGF2 is a key determinant of vascular sprouting and hence critical to luteal development.

FGF2 is crucial for the development of bovine luteal endothelial networks in vitro.

The development of the corpus luteum requires angiogenesis, and involves the complex interplay between factors such as vascular endothelial growth factor A (VEGFA), fibroblast growth factor 2 (FGF2) and platelet-derived growth factor (PDGF). However, the relative role of these factors remains to be elucidated. This study used a new physiologically relevant mixed luteal cell culture system to test the hypotheses that: a) FGF2 and VEGFA are critical for bovine luteal angiogenesis; and b) local luteal PDGF signalling stimulates the formation of endothelial networks. Cells were treated with receptor tyrosine kinase inhibitors against VEGFA (SU1498), FGF2 (SU5402) or PDGF (AG1295) activity. After 9 days in culture, endothelial cells were immunostained for von Willebrand factor (VWF) and quantified by image analysis. Highly organised intricate endothelial networks were formed in the presence of exogenous VEGFA and FGF2. The inhibition of FGF2 activity reduced the total area of VWF staining versus controls (>95%; P<0.001). Inhibition of VEGF and PDGF activity reduced the endothelial network formation by more than 60 and 75% respectively (P<0.05). Progesterone production increased in all treatments from day 1 to 7 (P<0.001), and was unaffected by FGF2 or PDGF receptor kinase inhibition (P>0.05), but was reduced by the VEGF receptor inhibitor on days 5 and 7 (P<0.001). In conclusion, this study confirmed that VEGF signalling regulates both bovine luteal angiogenesis and progesterone production. However, FGF2 was crucial for luteal endothelial network formation. Also, for the first time, this study showed that local luteal PDGF activity regulates bovine luteal endothelial network formation in vitro.

Supra-basal progesterone concentrations during the follicular phase are associated with development of cystic follicles in dairy cows.

The objective of this study was to test the hypothesis that supra-basal concentrations of progesterone during the follicular phase are associated with the development of follicular cysts. Twenty-five non-lactating dairy cows were used in the study, which was performed over five identical replicate trials. Luteolysis was induced during the mid-luteal phase. Transrectal ultrasonography was performed daily to determine the occurrence/timing of ovulation. Plasma samples were collected for progesterone, oestradiol and luteinizing hormone (LH) analysis. Three cows failed to ovulate (cystic anovulatory) but did ovulate in a subsequent replicate (cystic ovulatory). Eight cows from the appropriate replicates were used as control cows (normal group). Follicular growth patterns and plasma oestradiol concentrations were similar between the three groups. However, the plasma progesterone concentrations during the follicular phase were twofold higher in the cystic anovulatory group (P < 0.01). Furthermore, no LH surge was detected in these animals. While LH pulse amplitude was similar between groups, LH pulse frequency in the cystic anovulatory group was attenuated (P < 0.05). In conclusion, the formation of follicular cysts were preceded by elevated plasma progesterone concentrations and the suppression of the LH surge.