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B Meinecke

Publications and source records attributed to B Meinecke.

At least 19 recordsLinked to original sources
PubMed2003

MAPK/ERK kinase (MEK) signalling is required for resumption of meiosis in cultured cumulus-enclosed pig oocytes.

Resumption of meiosis of mammalian oocytes is facilitated by the maturation promoting factor (MPF) and accompanied by activation of mitogen activated protein kinases (MAPK) which are phosphorylated by the MAPK kinase (MEK). In this study we examined the effects of PD 98059, which inhibits the activity of MEK, on in vitro maturation of pig oocytes. Cumulus-oocyte complexes (COCs) were cultured in the presence or absence of the drug (50 microM) for various time periods. To elucidate the influence of cumulus cells, COCs were first cultured in inhibitor-free medium, subsequently denuded, and incubated further in PD 98059 supplemented medium. Reversibility of drug action as tested following PD 98059 treatment of COCs by transferring them to drug-free medium. Culture of COCs in medium supplemented with PD 98059 prevents resumption of nuclear maturation in the majority of COCs. This inhibition was reversible and accompanied by a non-activation of both MAP and MPF. Addition of the MEK inhibitor to extracts of in vitro matured oocytes revealed that the kinase activities were not directly influenced by the inhibitor, suggesting a link between MAP and MPF kinases. Preincubation of COCs in inhibitor-free medium for 6 h followed by further culture of COCs or denuded oocytes in the presence of PD 98059 for various periods resulted in elevated MAP and MPF kinase activities, indicating an early and transient MEK signalling in the oocyte itself. These results support the idea that MAP and MPF are involved in the induction of germinal vesicle breakdown in porcine oocytes.

Animals↗
PubMed2003

A mola hydatidosa coexistent with a foetus in a bovine freemartin pregnancy.

Molar transformations of the bovine placenta are extremly rare phenomenona and the aetiology of this genuine placental disease is still unknown. In the present study, an uncommon case of a German Holstein Friesian foetus co-twinned with a hydatidiform mole is described. Cytogenetic and fluorescence in situ hybridization analysis of cell cultures as well as prove of the presence of the SRY gene sequence revealed a heterosexual twin pregnancy. A chimeric condition of the mole was also established. In addition, an XO cell population was detected in the co-twin as well as in the mole. Upon examination of microsatellites of the parents, the mole and the co-twin an androgenetic origin of the mole is suggested, supporting the hypothesis that molar transformation of the bovine placenta may be caused by an androgenetic origin. Furthermore, the present observation demonstrates that the freemartin condition in cattle can be induced even in cases where severe placental transformations had subsequently occurred and no foetus proper could be detected at delivery.

Animals↗
PubMed2001

Kinetics of meiotic progression, M-phase promoting factor (MPF) and mitogen-activated protein kinase (MAP kinase) activities during in vitro maturation of porcine and bovine oocytes: species specific differences in the length of the meiotic stages.

The kinetics of nuclear maturation, M-phase promoting factor (MPF) and mitogen-activated protein kinase (MAP kinase) activities during in vitro maturation of porcine and bovine oocytes were examined. A further objective was to determine the duration of the meiotic stages during the maturation process. Porcine and bovine cumulus-oocyte complexes (COCs) were incubated in TCM 199 supplemented with 20% (v/v) heat inactivated fetal calf serum (FCS), 0.05microg/ml gentamycin, 0.02mg/ml insulin, 2.5microg/ml FSH and 5microg/ml LH. COCs were removed from the culture media in hourly intervals starting immediately after recovery from the follicle until 24 (bovine) or 48h (porcine) of culture. Oocytes were either fixed to evaluate the maturation status or the activity of MPF, assessed by its histone H1 kinase activity, and MAP kinase were determined by a radioactive assay simultaneously. In oocytes of both species, the MPF activity oscillated during the culture period with two maxima corresponding with the two metaphases: between 27-32 and after 46h (porcine) and between 6-9 and after 22h (bovine). There was a temporary decline in activity after 33-38 (porcine) and after 19h (bovine), which corresponded with anaphase I and telophase I. MAP kinase activity increased during the whole culture period and reached maximum levels after 47 (porcine) and after 22h (bovine). In porcine oocytes, the MAP kinase was activated before GVBD and MPF activation. In bovine oocytes, MPF and MAP kinase were activated at approximately the same time as the GVBD (8-9h of incubation). In average porcine, oocytes remain 23.4h in the germinal vesicle (GV) stage (13h in GV I, 5.7h in GV II, 3.2h in GV III and 1.5h in GV IV), 0.9h in diakinese, 9.6h in the metaphase I, 2.8h in anaphase I and 1.9h in telophase I of the first meiotic division. In bovine oocytes, the temporal distribution of the meiotic stages were 8.5h for the GV stage, 1.2h for diakinese, 8.3h for metaphase I, 1.6h for anaphase I and 1.9h for telophase I. These results indicate that the duration of the meiotic stages differs between the species and that MAP kinase is activated before MPF and GVBD in porcine oocytes.

Animals↗
PubMed2001

Ultrasonic study of follicular dynamics following superovulation in German Merino ewes.

Ewes are commonly superovulated with a single dose of eCG or multiple doses of pFSH. It would be convenient and less expensive to use a single dose of FSH, but results of various trials have been controversial. We wished to investigate ovarian dynamics using ultrasonography after superovulation with a single dose of pFSH and hMG as compared with a single dose of eCG. Estrus was synchronized during the breeding season with fluorogestone acetate-containing intravaginal sponges in adult German Merino ewes (n = 38). They were superovulated with single doses of pFSH (17 mg; n = 10), hMG (600 IU FSH and 600 IU LH; n = 9) or eCG (1250 IU; n = 10) given at the time of sponge removal, or pFSH (17 mg; n = 9) given 36h before sponge removal. Follicular and luteal development were observed by ultrasonic scanning every 8 h from the gonadotrophin injection until the end of estrus, and then once daily until Day 6 after estrus. Jugular venous blood was collected starting immediately before and 1 h after superovulation treatment, then twice daily until the end of estrus and once daily for the following 7 days. Concentrations of estradiol-17beta (E2) and progesterone (P4) were measured in plasma. Differences in the follicular dynamics of the 4 superovulation groups were obvious. The functional duration of the pFSH action was estimated to last approximately 48 h, whereas eCG and hMG were active for up to 72 h. The diameter of the ovulatory follicles proved to be smaller than it was described for unstimulated ewes. Single applications of pFSH or hMG can induce a superovulatory response, although the post-estrus progesterone profile revealed a high premature luteal regression rate in the different superovulation groups. Premature corpus luteum regression could not be seen by ultrasonography at this early stage of the luteal phase, indicating that the technique may fail to detect these corpora lutea in an embryo transfer program. However, ultrasonography represents a suitable method to observe follicular dynamics following different superovulation regimens in sheep.

Administration, Intravaginal↗
PubMed2001

Ultrasonic survey of follicular development following superovulation with a single application of pFSH, eCG or hMG in goats.

During the breeding season, 42 adult German Improved Fawn nanny goats were superovulated with a single administration of pFSH, hMG or eCG at the end or a single dose of pFSH 36h before the end of estrus synchronization. Development of follicles and corpora lutea were observed by ultrasonic scanning of the ovaries every 8h from gonadotrophin treatment, until the end of estrus and once daily for the following 6 days. Differences in follicular dynamics could be realized in the four superovulation groups, and the duration of the stimulatory action following the single gonadotrophin challenge was estimated to last for 40-72h in the case of pFSH and to exceed 72h in the case of hMG and eCG treatment groups. Corpora lutea could first be detected 3 days after estrus, whereas an exact count was not possible until day 6. The ovulation rates were satisfactory, suggesting that a single injection of pFSH or hMG provides an adequate stimulus to induce a superovulatory reaction. Premature regression of corpora lutea could not be identified ultrasonographically at these early stages of the luteal phase. However, ultrasonography is a suitable method to follow follicular dynamics after superovulation and to estimate the superovulatory response in goats.

Journal Article↗
PubMed2001

Estradiol-17beta and progesterone in the peripheral blood plasma of goats following superovulation with a single dose of pFSH, hMG or eCG.

During the breeding season, 42 adult German Improved Fawn nanny goats were superovulated with a single dose of pFSH, hMG or eCG at the end or a single application of pFSH 36h before the end of synchronization treatment using flugestone acetate (FGA). Plasma sampling was performed immediately before and 1h after gonadotrophin treatment, twice daily during pre-estrus and estrus and once daily during post-estrus in order to determine peripheral estradiol-17beta and progesterone levels. During that period, ovarian dynamics was followed by serial ultrasound scans (8h interval during pre-estrus and estrus and once daily during post-estrus). Estradiol-17beta profiles differed between the treatment groups exhibiting significantly positive correlations between the mean estradiol-17beta concentrations and the numbers of developing large and medium-sized follicles during estrus. The early bolus application of FSH 36h before the end of synchronization treatment induced an additional advanced estradiol-17beta peak during gestagen dominance. A sharp decrease of estradiol-17beta at the end of estrus seems to play a major role for normal luteal development. Progesterone profiles during the early luteal phase revealed high premature luteal regression. An early progesterone increase was accompanied by low premature regression rates.Although simple B-mode ultrasonography is suitable to follow follicular growth patterns and to determine the ovulation rate following different superovulation regimen endocrinological supervision is required in order to detect a premature corpus luteum insufficiency.

Journal Article↗
PubMed2001

Roscovitine, a specific inhibitor of cyclin-dependent protein kinases, reversibly inhibits chromatin condensation during in vitro maturation of porcine oocytes.

In the present study the effects of roscovitine on the in vitro nuclear maturation of porcine oocytes were investigated. Roscovitine, a specific inhibitor of cyclin-dependent protein kinases, prevented chromatin condensation in a concentration-dependent manner. This inhibition was reversible and was accompanied by non-activation of p34cdc2/histone H1 kinase. It also decreased enzyme activity of MAP kinase, suggesting a correlation between histone H1 kinase activation and the onset of chromatin condensation. The addition of roscovitine (50 microM) to extracts of metaphase II oocytes revealed that the MAP kinase activity was not directly affected by roscovitine, which indicates a possible link between histone H1 and MAP kinase. Chromatin condensation occurred between 20 and 28 h of culture of cumulus-oocyte complexes (COCs) in inhibitor-free medium (germinal vesicle stage I, GV1: 74.6% and 13.7%, respectively). Nearly the same proportion of chromatin condensation was detected in COCs incubated initially in inhibitor-free medium for 20-28 h and subsequently in roscovitine-supplemented medium (50 microM) for a further 2-10 h (GV I: 76.2% and 18.8%, respectively). This observation indicates that roscovitine prevents chromatin condensation even after an initial inhibitor-free cultivation for 20 h. Extending this initial incubation period to > or = 22 h led to an activation of histone H1 and MAP kinase and increasing proportions of oocytes exhibiting chromatin condensation in the presence of roscovitine. It is concluded that histone H1 kinase is involved in the induction of chromatin condensation during in vitro maturation of porcine oocytes.

Animals↗
PubMed2001

Histone H1 and MAP kinase activities in bovine oocytes following protein synthesis inhibition.

In vitro nuclear maturation is associated with known activity profiles of the M-phase promoting factor (MPF) and the mitogen-activated protein (MAP) kinases, which are two key regulators of mitotic and meiotic cell cycles. Initiation of meiotic resumption in vitro can be prevented by cycloheximide treatment and after removal of the inhibitor germinal vesicle breakdown takes place nearly twice as fast as in untreated controls. In this study experiments were conducted in order to examine the chromosome condensation status and the dynamics of MPF and MAP kinase activities after cycloheximide treatment (10 microg/ml) of cumulus-enclosed oocytes for 17 and 24 h, respectively, and subsequent culture in inhibitor-free medium for various times. Bovine oocytes displayed variations in the degree of chromosome condensation at the end of the inhibitor treatment phase. Following removal of the inhibitor germinal vesicle breakdown occurred after 4-5 h of subsequent culture in inhibitor-free medium. MPF and MAP kinase exhibited low activities during the first 1-3 h following cycloheximide treatment. Increasing levels of enzyme activities were detected 4-7 h following cycloheximide treatment for 17 and 24 h, respectively, and subsequent culture in inhibitor-free medium. The patterns of enzyme activities corresponded with the accelerated nuclear maturation process. It can be concluded that cycloheximide treatment does not lead to a more synchronous course of nuclear maturation and that the activities of both, MPF and MAP kinase are initiated at least 2-5 h earlier in comparison with untreated oocytes.

Animals↗
PubMed1999

[Effect of the administration of PGF2 alpha synchronously with insemination on the pregnancy rate in mares in an insemination program].

Investigations in different species including the horse have demonstrated that prostaglandin F2 alpha (PGF2 alpha) is involved in initiating uterine contractions occurring during mating and artificial insemination (A.I.). Uterine contractions play an important role with respect to the sperm transport within the female genital tract. The objective of the present investigation was to evaluate whether the administration of PGF2 alpha (Dinoprost) synchronously to A.I. could have a positive effect on the pregnancy rate in mares. A field study including 346 warmblood-mares (age two to 20 years) belonging to a private studfarm was conducted during the breeding season 1996. The mares were assigned to two groups, group A: mares with spontaneous ovulation, group B: mares in which the ovulation was induced by a GnRH-analog-implant (Deslorelin). PGF2 alpha (Dinoprost) was administered either intramusculary (i.m., 5.0 mg) or intrauterine (i.ut., 0.5 mg diluted in 1.9 ml isotonic NaCl-solution and added to the semen dosis). The study was carried out in a double-blind fashion using isotonic NaCl-solution as a placebo. The mares of each group were randomly assigned to one of the two treatments (i.m. vs. i.ut.). The following first cycle pregnancy rates (day 18) were obtained in mares treated and inseminated once per oestrus: group A1 (PGF2 alpha, i.m.): 54.5% (n = 33); group A2 (placebo, i.m.): 69.7% (n = 33); group A3 (PGF2 alpha, i.ut.): 65.4% (n = 26); group A4 (placebo, i.ut.): 69.8% (n = 32); group B1 (PGF2 alpha, i.m.): 56.5% (n = 46); group B2 (placebo, i.m.): 29.6% (n = 27); group B3 (PGF2 alpha, i.ut.): 66.7% (n = 45); group B4 (placebo, i.ut.): 60.0% (n = 30). The pregnancy rates did not differ between the different groups with the exception of group B2 (p < 0.05). In mares treated repeatedly during the oestrus period (group A, n = 88; group B, n = 23), the pregnancy rates did not differ significantly between treatment and control groups. From the results obtained it is concluded that the PGF2 alpha-application did not show an effect on the pregnancy rate. Further factors influencing the results to a small degree were the stallions, semen age and quality and frequency of insemination per oestrus.

Animals↗
PubMed1997

Prevalence of carcinoma in situ of the testis in 207 oligozoospermic men from infertile couples: prospective study of testicular biopsies.

OBJECTIVE: To investigate the prevalence of carcinoma in situ of the testis in a group of oligozoospermic men from infertile couples. DESIGN: A consecutive group of oligozoospermic men from infertile couples were offered bilateral testicular biopsy. The observed prevalence of carcinoma in situ was compared with the expected prevalence of testicular cancer in a corresponding age matched population of Danish men, assuming all untreated cases of carcinoma in situ progress to tumour stage. This calculation was based on data from the Danish Cancer Registry. SUBJECTS: 207 men aged 18-50 years who had sperm density below 10 million/ml in two samples within the previous 2 years or sperm density below 20 million/ml in two samples within the previous 2 years and a history of cryptorchidism or one or two atrophic testicles (orchidometer volume less than 15 cm3), or both. INTERVENTIONS: Bilateral testicular biopsies. MAIN OUTCOME MEASURES: Carcinoma in situ in the biopsy specimen. RESULTS: No case of carcinoma in situ was found among the 207 men. The expected number in a normal age matched population of corresponding size was 0.8. CONCLUSIONS: There is no increase in risk of carcinoma in situ of the testis in moderately oligozoospermic men of couples referred because of infertility.

Adolescent↗
PubMed1995

Comparative analysis of the polypeptide pattern of cumulus cells during maturation of porcine cumulus oocyte complexes in vivo and in vitro.

The protein patterns of porcine cumuli oophori matured as intact cumulus oocyte complexes either in vivo or in vitro with or without FSH and LH for 46 h were investigated. In in vivo-matured cumuli oophori, a 53 kDa band disappeared after 24 h maturation, but reappeared at 46 h. Furthermore, the production of a polypeptide with a relative molecular mass of 44,000 ceased and the appearance of 2 other proteins with relative molecular masses of 38,000 and 28,000 was observed. In cumuli oophori matured in vitro with or without addition of FSH and LH the 53 kDa band ceased after a culture period of 12 h. This band was produced again after a culture period of 46 h. In contrast, the polypeptide with the relative molecular mass of 44,000 ceased only in cumuli oophori cultures supplemented with FSH and LH, and the 2 proteins of M(r) 38,000 and 28,000 were detected only in the protein profiles of mature cumuli cultured with FSH and LH. It is concluded that the addition of FSH and LH to the culture medium is necessary for cumuli oophori to synthesize a protein pattern, which corresponds closely to that produced by cumuli oophori matured in vivo.

Animals↗
PubMed1994

Identification of mouse ZP3 protein in mammalian oocytes with antisera against synthetic ZP3 peptides.

The mouse zona pellucida (ZP) protein ZP3 plays an important role in the process of fertilization by mediating sperm binding and the acrosome reaction. ZP3 primary structures are highly conserved, as revealed by cDNA cloning. We raised antisera against synthetic peptides that are either conserved in the structure of ZP3 from different mammalian species (AS ZP3-5 and AS ZP3-6) or specific for mouse ZP3 (AS ZP3-2). In ovary sections, AS ZP3-2 revealed immunoreactivity only to mouse ZP. AS ZP3-5 and AS ZP3-6 reacted with mouse, human, rat, hamster, porcine, and bovine ZP proteins. In porcine oocytes, immunoreactive material was highly abundant in the ooplasm. Immunoblots showed that antiserum AS ZP3-5 recognized the mouse ZP3 protein. In porcine ZP preparations, AS ZP3-5 recognized a 53-kDa ZP protein. No reaction was observed with purified porcine ZP3 alpha or with ZP3 beta. Immunofluorescence studies revealed that AS ZP3-5 and AS ZP3-6 antibodies react with ZP of isolated porcine and human oocytes. Our results show that antisera against synthetic mouse ZP3 peptides can be used as markers for the identification of ZP3-like proteins in mammalian oocytes and might be useful tools for the evaluation of ZP integrity and ZP3 function.

Amino Acid Sequence↗
PubMed1993

Effects of alpha-amanitin on nuclear maturation of porcine oocytes in vitro.

The effects of alpha-amanitin on cumulus enclosed and denuded porcine oocytes exposed to this heterogeneous nuclear RNA (hnRNA) synthesis inhibitor at different times (0, 0.5, 1, 2, 4, 6, 8, 12 and 20 h) after the start of culture was investigated. A further objective was to determine the sequence of nuclear progression after removing the inhibitor. The addition of 10 micrograms alpha-amanitin ml-1 to a gonadotrophin containing medium (10 iu PMSG ml-1 in TCM 199) at 0, 0.5 or 1 h after the onset of culture prevented cumulus expansion, and only 4.4, 6.4 and 3.5% of oocytes underwent germinal vesicle breakdown. This inhibitory effect was considerably reduced by delaying the addition of the drug to the culture medium for 2-8 h (2 h: 34.9%, 4 h: 53.5%, 6 h: 46.9%, 8 h: 59.2% germinal vesicle breakdown), and no inhibition of nuclear maturation was observed when alpha-amanitin was added after 12 or 20 h following explantation of the oocytes. When cumulus-oocyte complexes were cultured for > or = 2 h in inhibitor-free medium and then transferred to medium supplemented with alpha-amanitin, full cumulus expansion was observed in all cases, at the end of the 44 h culture. Denudation of the oocytes before culture in either medium supplemented with alpha-amanitin or microinjection of alpha-amanitin into the ooplasm at concentrations of 1.0 and 10.0 mg ml-1 remained without any effect on nuclear progression.(ABSTRACT TRUNCATED AT 250 WORDS)

Amanitins↗
PubMed1992

Serum placental protein 14 (PP14) reflects endometrial status during hormone replacement therapy.

Healthy post-menopausal women were randomly assigned to treatment groups receiving 28 day treatment cycles of oestradiol valerate (2 mg, days 1-28) sequentially combined with levonorgestrel (75 micrograms, days 17-28) (n = 19); oestradiol valerate (2 mg, days 1-28) continuously combined with cyproterone acetate (1 mg, days 1-28) (n = 18), or placebo (n = 22). Treatment continued for 2 years. After therapy, the women receiving the sequential combination had an early secretory phase (74%) or atrophic endometrium (26%). All women receiving the continuous combination or placebo had inactive or atrophic endometrium, or the tissue was inadequate for assessment. Biochemical parameters of endometrial secretion [oestradiol dehydrogenase (EDH), isocitrate dehydrogenase (ICDH)] measured in endometrial tissue and placental protein (PP14) measured in serum were all low in the groups receiving the continuous combination and placebo. During sequential treatment, all biochemical parameters showed significantly higher mean values. Serum PP14 accurately reflected this pattern. Furthermore, in the sequentially treated group, serum PP14 correlated highly significantly with EDH (r = 0.70; P less than 0.001) and ICDH (r = 0.57; P = 0.01). These correlations were of the same magnitude as the correlations between the endometrial markers, which indicates that serum PP14 reflects the endometrial status. Furthermore, serum PP14 measurements at 3 months and at 2 years of treatment were highly correlated, reflecting the long-term validity of the measurement. The present data suggest that PP14 measured in serum may be used to assess endometrial status. Further studies are required to determine whether serum PP14 will discriminate pathological endometrial conditions.

Cyproterone Acetate↗
PubMed1992

Sequential estrogen and progestogen therapy: assessment of progestational effects on the postmenopausal endometrium.

Healthy postmenopausal women were randomly assigned to groups receiving 28-day treatment cycles of estradiol (E2) valerate (2 mg, days 1-21) combined with medroxyprogesterone acetate (10 mg, days 12-21) (N = 18), 17 beta-estradiol (1.5 mg, days 1-24) combined with desogestrel (150 micrograms, days 13-24) (N = 20), or placebo (N = 18). The progestational effects on the endometrium were assessed by histology, uterine bleeding pattern, and biochemical markers of secretion measured in endometrial tissue (E2 and isocitrate dehydrogenase) and serum (placental protein 14). After 2 years of therapy, 24 women in the hormone groups had secretory endometrium and 13 had atrophic endometrium; in the placebo group, the results were one and 15, respectively. Withdrawal bleeding generally started between days 9-12 after the addition of progestogen in the E2-medroxyprogesterone acetate group, and between days 14-17 in the E2-desogestrel group. All three biochemical markers of secretion were increased in each of the hormone-treated groups compared with the placebo group (P less than .01-.001). Serum placental protein 14 was twice as high in the secretory as in the atrophic phase (P less than .01). Isocitrate dehydrogenase, but not E2 dehydrogenase, was also higher in the secretory phase (P less than .05). Only serum placental protein 14 was significantly related to the uterine bleeding pattern (P less than .01). We conclude that serum placental protein 14 reflects both endometrial histology and bleeding pattern and may be a useful marker of progestational effects on the endometrium. The markers of secretion measured in endometrial tissue are not as reliable for endometrial histology or bleeding pattern.

Desogestrel↗
PubMed1991

Granulomas of the appendix: is it Crohn's disease?

An epidemiologic study was performed 1) to estimate the occurrence of epithelioid granulomas in the appendix wall among patients in whom an appendectomy had been performed, 2) to identify patients with granulomas in the appendix who had symptoms and history compatible with Crohn's disease, and 3) to estimate the long-term prognosis. Within a 5-year period 6051 patients in Copenhagen County underwent appendectomy. Six patients (0.1%) had epithelioid granulomas of the appendix (0.2 per 10(5) inhabitants per year). Follow-up of the six patients for 9-11 years (median, 9.5 years) showed that all had been free of gastrointestinal symptoms since the operation. Among the 373 patients diagnosed as having Crohn's disease in Copenhagen County between 1962 and 1987, 3 patients had their disease initially confined to the appendix. Follow-up in these patients showed no recurrence within a median of 6 years (range, 4-7 years). Patients with epithelioid granulomas of the appendix have an excellent long-term prognosis, which could be explained by the fact that the condition seems to be unrelated to Crohn's disease.

Adolescent↗
PubMed1990

[The endocrine status of clinically conspicuous mares during the peripartum period].

The aim of the present investigations was to characterize the endocrine changes in the peripheral plasma during the periparturient phase of mares with a known history of obstetrical disorders. Blood plasma samples from 9 mares (8 mares during parturition, 1 mare during abortion) were collected and the following steroid hormones were radioimmunologically determined: progesterone (P4), dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEA-S), estrone (E1), estrone sulfate (E1-S), estradiol-17 beta (E2), estriol (E3), cortisol and transcortin. In general, with the exception of cortisol, DHEA and transcortin, all steroid hormone levels declined significantly after parturition. Mean plasma concentrations of DHEA-S, the direct fetal precursor of estrone, were 6 times higher than DHEA. However, DHEA-S levels varied considerably between all mares as well as between daily values of the same mare. Levels of E1-S were found to be about thousand times higher than those of E1, E2, and E3. The rather low concentrations of E3 suggest that this hormone is mainly produced by peripheral conversion and that in the horse fetus the 16 alpha-hydroxylation of DHEA-S is lacking. Despite the fact that most of the examined mares showed signs of severe disease none of the investigated steroid hormones indicated any disturbances of gestation. It is concluded that, from the clinical point of view, serial determinations of E1-S plasma levels are the best way to prove the fetal well-being. However, it should be stressed, that even the E1-S values are no indicators for the onset of parturition or abortion.

Abortion, Veterinary↗