Effect of insulin on human chorionic gonadotrophin secretion by placental explants

The effect of physiological concentrations of insulin (5–50µU/ml) was tested on human chorionic gonadotrophin (HCG)secretion by first trimester (7–9 weeks) and term placentalexplants using both static and dynamic culture models. In staticcultures, insulin exerted a significant biphasic inhibitoryeffect (80% at 5 µU/ml and 40% at 50 µU/ml) on HCGsecretion by placental explants. At approximate fasting plasmalevels, 25 µU/ml insulin added to superfused explantsfor 8 min also had a rapid inhibitory effect. A delayed inhibitoryeffect on HCG pulsatility was also observed using 25 µU/mlinsulin, with a 2-fold decrease in HCG pulse amplitude and a4-fold decrease in the area under the curve following overnightpre-incubation (P < 0.01). Insulin had no effect in staticcultures at term. The effect of insulin-like growth factor (IGF-I)and fibroblast growth factor (bFGF) on HCG secretion in staticcultures was not statistically significant. In conclusion, physiologicalconcentrations of insulin inhibit HCG secretion in first trimesterplacenta in vitro. This effect is gestational age dependentand specific since it is not mimicked by IGF-I or bFGF. Thus,insulin may be an important modulator of trophoblastic HCG secretionduring early pregnancy.     

In-vivo and in-vitro assessment of the influence of ritodrine and oxytocin on the placental secretion of human chorionic gonadotrophin and placental lactogen

The purpose of this study was to evaluate, in vivo and in vitro,the influence of ritodrine and oxytocin on the placental releaseof human chorionic gonadotrophin (HCG) and placental lactogen(HPL). The in-vivo study was performed on maternal sera collectedbefore and 1 h after the onset of either ritodrine treatment(50µg i.v/min; administered to 15 women at risk of prematurelabour) or oxytocin infusion (2 mU i.v./min; administered to21 women for acceleration of slow labour). The in-vitro studywas performed on human term placental explants incubated inthe presence of 4–400 ng ritodrine/ml or 15–1500UiV oxytocin/ml. HCG and HPL were measured by radio-immunoassayon maternal sera and incubation media. Maternal circulatingconcentrations of HCG and HPL remained unaffected after 1 hof ritodrine or oxytocin treatment The in-vitro release of HCGand HPL by placental explants was not modified when ritodrineor oxytocin was added to the incubation media. The lack of influenceof ritodrine and oxytocin on the placental secretion of HCGand HPL suggests that β₂-adrenergic and oxytocin receptorsare not involved in the releasing process.     

Effect of 1-34 human parathyroid hormone upon first trimester placental human chorionic gonadotrophin secretion in vitro: potentiation by epidermal growth factor

Human chorionic gonadotrophin (HCG) secretion by the early placentais under multifactorial control. Epidermal growth factor (EGF)has been reported to be involved in regulating the formationand secretion of HCG by first trimester placental explants inculture. The effect of the amino-terminal fragment of parathyroidhormone (1–34 PTH), a calciotrophic factor upon HCG secretion,and its possible interaction with EGF were examined in thisstudy, both in static cultures and in superfusion, where ithas previously been demonstrated that HCG secretion is spontaneouslypulsatile. Gestational age-dependent effects of 1–34 PTHwere noted in both models. In static cultures, 1–34 PTHstimulated HCG secretion in 7–9 week placenta, in a biphasicfashion, the maximal effect being noted at 10–25 ng/mlconcentrations (250–270%), while at 1 and 100 ng/ml, theeffect was mild. In superfusion, the effect of 1–34 PTHadded overnight was also stimulatory, as shown by the significantlyincreased pulse amplitude and area under the curve. Effectsof 1–34 PTH at 11–14 weeks were inhibitory. In staticcultures at 7–9 weeks, the stimulatory effect of 25 ng1–34 PTH was increased by 70% when EGF (100 ng/ml) wasadded. However at 11–14 weeks, this combined effect wasinhibitory. We conclude that 1–34 PTH has an endocrineeffect on secretion of HCG by the first trimester placentaltissue, and this effect is potentiated by the addition of EGF.     

Endocrinology: Luteal function following ovulation induction in polycystic ovary syndrome patients using exogenous gonadotrophins in combination with a gonadotrophin-releasing hormone agonist

The luteal phase was studied in 12 polycystic ovary syndrome(PCOS) patients following ovulation induction using exogenousgonadotrophins combined with a gonadotrophin-releasing hormoneagonist (GnRH-a). Human menopausal gonadotrophin (HMG) was precededby 3 weeks of treatment with GnRH-a (buserelin; 1200 µg/dayintra-nasally) and administered in a step-down dose regimenstarting with 225 IU/day i.m. GnRH-a was withheld the day beforeadministration of human chorionic gonadotrophin (HCG; 10 000IU i.m.). Blood sampling and ultrasound monitoring was performedevery 2–3 days until menses. The luteal phase was significantlyshorter in PCOS patients as compared to eight regularly cyclingcontrols: 8.8 (3.3–11.4) days [median(range)] versus 12.8(8.9–15.9) days (P = 0.01). Median peak values for progesteronedid not show significant differences comparing both groups:52.3 (17.1–510.3) nmol/l versus 43.0 (31.2–71.1)nmol/l, respectively (P = 0.8). The interval between the dayof the progesterone peak and return to baseline was significantlyshorter in the PCOS patients than in controls: 2.5 (0.3–4.9)days versus 4.2 (3.9–10.5) days (P < 0.005). Luteinizinghormone (LH) concentrations during the luteal phase as reflectedby area under the curve were significantly lower in PCOS ascompared to controls: 4.4 (1.6–21.0) IU/l x days and 49.0(27.8–79.6) IU/l x days, respectively (P < 0.001).In conclusion, patients with PCOS may suffer from insufficientluteal phases after ovulation induction using HMG/HCG in combinationwith a GnRH-a. The corpus luteum apparently lacks the supportof endogenous LH and may be stimulated only by the pre-ovulatoryinjection of HCG. Potential involvement of adjuvant GnRH-a medicationor HCG itself in luteal suppression of endogenous gonadotrophinsecretion, and the importance of luteal function for pregnancyrates following treatment, warrant further studies.     

Ovary and Ovulation: An aminopeptidase inhibitor, bestatin, enhances gonadotrophin-stimulated ovulation in mice

The role of aminopeptidases in follicular growth and/or ovulationin vivo was examined. We injected an inhibitor of cell-surfaceaminopeptidases, bestatin (4 mg/ml, 100 µl), i.p. fourtimes during 2 days into 20 day old female ICR mice, in whichfollicular growth and ovulation were stimulated by pregnantmare's serum gonadotrophin (PMSG, 5 IU) and human chorionicgonadotrophin (HCG, 5 IU). The number of ovulated oocytes wasestimated by counting the number of oocytes in the oviduct 19h after HCG injection. The mean ± SD number of ovulatedoocytes in bestatln-treated mice was significantly higher thanthat in control mice [47.00 ± 18.13 (n = 26) versus 35.90± 10.14 (n = 28), P < 0.01]. To confirm the directeffect of bestatin on the ovary, bestatin (2 mg/ml, 3 µl)or its stereolsomer (2 mg/ml, 3 µl) with very weak inhibitoryactivity was unilaterally injected into the ovarian bursa 24h before the administration of PMSG. As a control, buffer (3µl) was injected into the contralateral bursa. In someexperiments, bestatin (2 mg/ml, 3 µl) was injected justbefore HCG administration. The administration of bestatin viathe ovarian bursa prior to PMSG administration significantlyincreased the number of ovulated oocytes per oviduct from thetreated compared with the contralateral ovary [23.70 ±9.61 versus 17.10 ± 5.83 (n = 25), P < 0.01], whereasits stereoisomer elicited no significant effects. The administrationof bestatin just before HCG administration also had no effect.These findings indicate that membrane-bound peptidase(s) presenton murine ovarian cells is an important regulating factor(s)of follicular growth and/or ovulation.     

Factors controlling spontaneous human chorionic gonadotrophin in superfused first trimester placental explants.

We have recently reported that secretion of human chorionic gonadotrophin (HCG) by placental explants in superfusion is pulsatile. In this study, the factors involved in regulation of spontaneous pulsatility were examined. In superfusion, observed secretion of HCG by isolated cells was continuous, without spontaneous episodic hormonal secretion. However, this was not due to diminished viability of the cells since these cells continued to secrete sex steroids. In addition, the stimulatory response of HCG to a highly effective dose of 10(-9) M gonadotrophin releasing hormone (GnRH) analogue was also maintained. Preincubation of explants with low concentrations of cycloheximide (10(-6)M) markedly reduced baseline HCG levels as well as pulse amplitude, suggesting that episodic hormone secretion is in part dependent on protein synthesis. Moreover, preincubation of explants with labelled leucine has shown that the secretion of placental proteins is also episodic in superfusion. The pattern was similar but not identical to that of HCG. Addition of 1 min pulses of CaCl2 caused a significant release of HCG by superfused explants, suggesting that HCG secretion occurs through the release of storage granules. It was concluded that for the expression of spontaneous pulsatile secretion of HCG cell to cell contact/communication is necessary. HCG secretion is likely to reflect exocytosis of storage granules. HCG pulsatility is partly dependent on protein synthesis and this intermittent type of secretion can be documented by overall protein secretion by the superfused explant.     

The effect of progesterone upon first trimester trophoblastic cell differentiation and human chorionic gonadotrophin secretion.

The effect of progesterone (P) upon first trimester placental secretion of human chorionic gonadotrophin (HCG) and cellular differentiation was studied using both static and kinetic methods. At 1 microM, P inhibited spontaneous episodic secretion of HCG when given in short pulses (1-4 min) to placental explants in superfusion. Both HCG pulse frequency and amplitude were reduced. At 0.1-0.01 microM P concentrations, the effect of HCG secretion was milder. P also blocked the maximally effective concentration 100 pM of gonadotrophin releasing hormone (GnRH) analogue, a known HCG stimulant, when given together with it for 1 min. This inhibitory effect lasted for 1 h after P administration. Progesterone at 1 microM, added daily for 1 week blocked HCG secretion by isolated trophoblastic cells in static culture. This inhibitory effect lasted until the fifth day. No effect on differentiation and long-term viability was noticed in P-treated cells. Incubation with 0.1-1.0 microM P did not affect HCG secretion by explants after 24 h. In contrast, the effect of 1 microM cortisol or 1 nM oestradiol was stimulatory. In conclusion, P exerts both a rapid and delayed inhibitory effect upon HCG secretion and production. It may do so by counteracting the stimulatory effect of endogenous GnRH on gonadotrophin secretion by the placenta.     

Placental and ovarian hormones in anembryonic pregnancy

The circulating levels of human chorionic gonadotrophin (HCG),pregnancy-associated plasma protein-A (PAPP-A), Schwangerschaftprotein 1 (SP-1), oestradiol and progesterone were measuredin 81 pregnant patients between 4 and 11 weeks gestation, followingin-vitro fertilization and embryo transfer. The patients weredivided as follows: singleton anembryonic pregnancies, n = 22;singleton pregnancies which spontaneously aborted followingthe demonstration of fetal heart activity, n = 7; and normalsingleton pregnancies, n = 52. The levels of all substancesmeasured were significantly reduced in women with anembryoniccompared to those with singleton pregnancies which proceededto term. The serum levels of SP-1, weeks 6–8 (P < 0.01);HCG, weeks 6–8 (P < 0.05); oestradiol, weeks 5–8(P < 0.05) and progesterone, weeks 6–8 (P < 0.05),were lower in anembryonic pregnancies than in those of pregnancieswhich spontaneously aborted. These differences may be a reflectionof the fact that miscarriage, after the demonstration of fetalheart activity, represents fetal demise at a later stage inpregnancy. In anembryonic pregnancies, significant associationswere found between HCG and both oestradiol and progesteronelevels from weeks 6 and 8, suggesting that in the absence ofan embryo, HCG is the prime determinant of steroid synthesisby the corpus luteum.     

Modification of pulsatile human chorionic gonadotrophin secretion in first trimester placental explants induced by polycyclic aromatic hydrocarbons.

The polycyclic aromatic hydrocarbons are major environmental pollutants. Benzo[a]pyrene and 3-methylcholanthrene are prominent members of this group of compounds. In the present study, we have examined the effect of these carcinogens/mutagens upon human chorionic gonadotrophin (HCG) secretion in the first trimester placenta in vitro. At 7-9 weeks in static cultures, exposure to 50 microM benzo[a]pyrene for 24 h increased beta-HCG secretion by placental explants. The effect after 6 h of incubation was less apparent. The effect of 5 microM benzo[a]pyrene at the two time points also was less significant than 50 microM benzo[a]pyrene. In explants exposed to 50 microM 3-methylcholanthrene, the effect on HCG secretion was also stimulatory. In superfusion of placental explants pretreated overnight with benzo[a]pyrene, there was a similar increase in the pattern of pulsatile beta-HCG secretion, as analysed by the area under the curve and the pulse amplitude, which was most evident at 24 h with the 50 microM dose. No significant effect on pulse frequency was noted. The effect of 50 microM 3-methylcholanthrene was also stimulatory. In order to determine the functional integrity of the explants treated with benzo[a]pyrene, the effect of 1 min pulses of 10(-10) gonadotrophin-releasing hormone (GnRH) analogue (a known HCG stimulator in superfusion) was tested, demonstrating that it increased beta-HCG secretion compared to controls. In addition, there was also an increase in whole HCG, as measured by the Tandem-R assay following exposure to benzo[a]pyrene. In conclusion, short-term exposure to carcinogens increases HCG secretion of placental explants in early pregnancy and this effect is maintained after removal of the xenobiotic.     

Molecular interactions during pregnancy: Placental mRNA expression of {alpha} and {beta} human chorionic gonadotrophin in early trisomy 18 pregnancies

The placental expression of human chorionic gonadotrophin (HCG)I- and ß-subunits was investigated in eight pregnanciespresenting with trisomy 18 and in 30 normal pregnancies at 11–15weeks gestation. In the control group, the median densitometricscores of placental ß-HCG and I-HCG mRNA were 1.23and 1.74 respectively. In the trisomy 18 group the median ß-HCGmRNA was significantly lower (0.16, Z = 2.29, P<0.05) but     

Patterns of secretion of human chorionic gonadotrophin by superfused placental explants and the embryo--placental relationship following maternal use of medications.

There is great concern regarding maternal exposure to medications, especially in the first trimester of pregnancy because of the possible teratogenic effects. In the present study we have examined the consequences of maternal drug exposure in vivo upon placental secretion patterns of human chorionic gonadotrophin (HCG) and the relationship between the embryo and placenta in vitro. This was examined in samples obtained from various drug-exposed women following elective pregnancy termination at 8-9 weeks. The patterns of HCG secretion in superfused placental explants were different from those seen in control explants (without use of any medication). This was shown by changes in the pulse pattern and pulse frequency. In addition, the exposure of placental explants to various embryonic tissues modified HCG secretion in static cultures. In superfusion, co-perfusion with embryonic spinal cord tissue increased HCG secretion as opposed to that seen in similar incubations made with embryonic spinal cord tissue obtained from healthy women. Thus, our data suggest that maternal drug exposure alters both spontaneous hormone secretion by the placenta and the recently described embryo--placental relationship in vitro.     

Stress-related hormones affect human chorionic gonadotrophin secretion from the early human placenta in vitro.

The effect of a physiological range of concentrations of three stress-related hormones, oxytocin (OT), arginine-vasopressin (AVP) and prolactin (PRL) was tested upon human chorionic gonadotrophin (HCG) secretion by placental explants from early pregnancy in static and superfusion cultures. In static cultures, OT and AVP significantly increased HCG secretion, whereas PRL had no effect. In superfusion, 1-min pulses of OT induced a significant (two- to 10-fold) rise in HCG pulse amplitude compared to the control. This effect of this neuropeptide was blocked by coadministration of a specific receptor antagonist. AVP also increased the glycoprotein pulse amplitude by two- to five-fold, but only with every second pulse administered. PRL pulses caused a progressive inhibition of spontaneous HCG pulsatility. In conclusion, stress-related hormones affect placental HCG secretion in vitro. The involvement of these factors in impairing early pregnancy development is suggested.     

Effect of beta-endorphin on human chorionic gonadotrophin secretion by placental explants.

In the present study the effect of physiological concentrations of beta-endorphin was examined upon human chorionic gonadotrophin (HCG) secretion by first trimester placental explants. Results show that at 7-9 weeks of gestation, beta-endorphin inhibited HCG secretion; a maximal suppression of 60% was noted at 5 x 10(-10) M concentrations, while fivefold lower or higher doses were less effective. This inhibitory effect was completely reversed by naloxone, an opiate receptor antagonist, indicating involvement of an opiate receptor in the action of beta-endorphin. The opioid peptide specificity was demonstrated by the failure of N-acetyl-beta-endorphin, a non-opiate analogue used at the same concentration range, to affect HCG secretion. Following the HCG peak, at 11 weeks however, the effect of beta-endorphin was stimulatory on HCG secretion, which suggests a gestational age-dependent effect of the opioid peptide. In conclusion, these data indicate that beta-endorphin, a mu and delta opioid receptor ligand, has a modulatory effect on HCG secretion in vitro in the young placenta.     

Induction of final follicular maturation and early luteinization in women undergoing ovulation induction for assisted reproduction treatment--recombinant HCG versus urinary HCG. The European Recombinant Human Chorionic Gonadotrophin Study Group

This multicentre, double-blind, double-dummy, randomized, parallel-groupstudy compared the efficacy and safety of recombinant humanchorionic gonadotrophin (rHCG) (Ovidrel^®) and urinary HCG(uHCG) (Profasi^®) for inducing final follicular maturationand early luteinization in women undergoing ovulation inductionfor assisted reproduction treatment. Following long down-regulationand stimulation with recombinant human FSH (rFSH) (Gonal-F^®),a total of 190 women received a single, s.c. injection of either250 µg rHCG or 5000 IU uHCG. For evaluable patients (n= 172), the mean number of oocytes retrieved per patient (primaryefficacy endpoint) was 11.6 for rHCG and 10.6 for uHCG (notsignificant). The mean number of mature oocytes was statisticallyhigher (P = 0.027) for the rHCG group than the uHCG (9.4 versus7.1). Serum progesterone concentrations on day 1 and days 6–7post-HCG, and serum HCG concentrations at all post-HCG timepoints were statistically significantly in favour of rHCG. Theclinical pregnancy rate was somewhat higher (not significant)in the rHCG group (33 versus 25%) as was the live birth rate(27 versus 23%, not significant). Both treatments were welltolerated, though the incidence of adverse events was significantlyhigher in the uHCG group (45.1 versus 22.7%, P = 0.0004). Theincidence of injection-site reactions was significantly lowerin the rHCG group (P = 0.0001). In conclusion, for triggeringovulation, rHCG seems to have significant advantages comparedwith uHCG in terms of number of mature oocytes retrieved, lutealprogesterone and local tolerance.     

Pregnancy: Reduced circulating placental protein concentrations during the first trimester are associated with preterm labour and low birth weight

Serum concentrations of human chorionic gonadotrophin (HCG),Schwangerschaftsprotein 1 (SP-1), pregnancy-associated plasmaprotein A (PAPP-A), progesterone and oestradiol were measuredat weekly intervals between the fifth (embryo transfer plus3 weeks) and 13th week of gestation during the first trimesterof pregnancies achieved following in-vitro fertilization (IVF)and embryo transfer in a group of women who delivered before(n = 8) or at term (n = 52). Those women who had a preterm deliveryhad significantly lower concentrations of PAPP-A (weeks 7–13;P = 0.0001–0.028) and SP-1 (weeks 6–8 and 10–12;P = 0.004–0.04). After correction of birth weight forsex and gestational age at delivery, preterm delivery was foundnot to be associated with growth retardation. However, comparisonof the circulating concentrations of the substances analysedin mothers who delivered babies of < 85% of the 50th centileof the normal range of birth weight for a given gestationalage and sex, with those who delivered babies of >85% revealedthat the concentrations of HCG (P = 0.012–0.04 on weeks6–9) and SP-1 (P = 0.003–0.03 on weeks 7, 9–13)were significantly lower in the former group. Weak, inconsistentassociations were found between the circulating concentrationsof HCG, SP-1 and PAPP-A and both corrected birth weight andgestational age at delivery. Thus, both the gestational ageat delivery and low birth weight may be related to impairedplacental development/function during the first trimester.     

Rapid diagnosis of early ectopic pregnancy in an emergency gynaecology service--are measurements of progesterone, intact and free {beta} human chorionic gonadotrophin helpful?

The clinical usefulness of measuring serum concentrations ofprogesterone, human chorionic gonadotrophin (HCG) and the free-subunit of HCG in distinguishing between early viable and non-viablepregnancy, before an accurate ultrasound diagnosis is possible,was evaluated in a prospective study of patients presentingto our emergency gynaecology service with a clinical suspicionof ectopic pregnancy. Patients were selected on the basis ofinitial HCG concentrations; samples with HCG 25–10 000IU/I were later analysed for progesterone and free HCG. Of the181 patients studied, 38 (21%) had an ectopic pregnancy, 108(60%) had a spontaneous abortion and 35 (19%) had a viable intra-uterinepregnancy. Concentrations of HCG and free HCG in the group withviable pregnancies were significantly higher than in the groupwith ectopic pregnancy (P < 0.001) and than those destinedto miscarry (P < 0.01). Progesterone concentrations werealso significantly higher in the viable versus the ectopic andthe spontaneous abortion groups (P < 0.001 in each case).Despite these highly significant differences there was a degreeof overlap such that it was impossible to devise a cut-off levelfor any hormone analysed, either singly or in combination, whichwould offer a clinically useful predictor of outcome.     

Steroid production in cultured thecal cells obtained from human ovarian follicles

During follicular maturation there is a co-ordinated hormonalregulation of the theca and granulosa cells. It is generallybelieved that granulosa cell proliferation and differentiationare promoted mainly by follicle stimulating hormone (FSH) andthat luteinizing hormone (LH) regulates the function of thetheca cells. The aim of the present study was to examine theeffect of LH/human chorionic gonadotrophin (HCG) on steroidproduction in human thecal cells. Isolated follicles (5–20mm) were obtained during the follicular phase of the menstrualcycle in 10 women undergoing gynaecological laparotomy for reasonsunrelated to ovarian pathology. The leading follicle(s) wasexcised and dispersed cells of the theca interna layer wereisolated through combined mechanical and enzymatic techniques.The thecal cells were cultured 4–6 days with and withoutLH/HCG. Medium levels of androstenedione, testosterone and progesteronewere measured by radioimmunoassay. Isolated thecal cells, culturedfor 6 days, showed a high sensitivity to stimulation by LH/HCG.Steroid secretion was highest during days 0–2 and thendeclined gradually. LH/HCG stimulated steroid production ina dosedependant way with the maximal stimulatory effect of LHat a concentration of 1–10 ng/ml, and of HCG at 0.01–0.1IU/ml. The important question, especially in clinical situations,of the optimal level of LH for normal follicular maturation,remains to be answered. The present study is compatible withthe view that thecal cell steroidogenesis in vivo is close tomaximally stimulated by normal basal LH levels.     

In-vitro development of in-vivo produced rhesus monkey morulae and blastocysts to hatched, attached, and post-attached blastocyst stages: morphology and early secretion of chorionic gonadotrophin

The earliest time of secretion of chorionic gonadotrophin (CG)by primate embryos and its role during preimplantation developmentand implantation are not clearly determined. We cultured in-vivofertilized/developed zona-intact, morphologically normal morulae(n = 11) and early blastocysts (n = 11), freshly recovered (bynon-surgical uterine flushing) on days 5 and 6 of pregnancy,respectively (day 0 = the day following LH surge), from non-superovulatednaturally bred rhesus monkeys (Macaca mulatta). Embryos werecultured for a minimum of 24 days in dishes containing 1 mlof CMRL-1066 supplemented with 20% bovine fetal serum in a humidifiedatmosphere of 5% CO₂ in air at 37°C. The culture mediumwas changed every 48 h. The percentage of hatched blastocysts,developed from morulae and early blastocysts, was 90.9; elapsedtimes (mean ± SEM) were 67.8 ± 4.4 h (morula)and 37.8 ± 3.6 h (blastocyst). The minimum number ofHoechst-stained cells/hatched blastocyst was 531. The mean diameter(± SEM) of cultured embryos increased from 180 µmat the beginning of culture to 374 ± 28 and 450 ±19 µm at the fully expanded and hatched blastocyst stages,respectively. Hatched blastocysts continued to expand (maximumdiameter: 1125 ± 25 µm); after an additional 94–96h they attached firmly to the serum-coated dishes and producedhighly proliferating multinucleate trophectodermal cells, extendingto a maximum diameter of 2–6 mm by 11–21 days ofculture. Biologically active CG in embryo-grown, serial spentmedia samples was measured in a mouse Leydig cell bioassay.The embryonic secretion of CG (ng/ml, mean ± SEM) commencedjust prior to hatching ( 0.014 ± 0.0), increased to 1.7± 0.5 after hatching but prior to attaching, and to 122.7± 45.5 by 5–11, 5108.7 ± 1706.0 by 10–17days, and decreased to 317.0 ± 201.4 by 16–40 daysin culture. These results show firstly that in-vivo producedrhesus monkey morulae and early blastocysts develop in vitroto hatched and attached blastocyst stages, exhibiting extensivetrophectodermal outgrowths. Secondly, the secretion of bioactiveCG commences from low levels during the pre-attaching blastocyststage, and increases exponentially after the attachment andtrophectodermal outgrowth of cultured embryos.     

Relationship of biochemical pregnancy to pre-ovulatory endometrial thickness and pattern in patients undergoing ovulation induction

In order to assess the relationship between pre-ovulatory endometrialthickness and pattern and biochemical pregnancy, the pregnancyoutcome was retrospectively analysed in 81 patients undergoingovulation induction evaluated by vaginal ultrasound on the dayof human chorionic gonadotrophin (HCG) administration or luteinizinghormone (LH) surge. Biochemical pregnancies occurred in 7/32(21.9%) pregnancies when endometrial thickness was <9 mm,compared to 0/49 when endometrial thickness was 9 mm on theday of HCG administration or LH surge (P < 0.0025). Clinicalabortions occurred in 5/32 (15.6%) pregnancies when endometrialthickness was 6–8 mm, compared to 6/49 (12.2%) when endometrialthickness was 6–8 mm (NS). Endometrial thickness was relatedto the cycle day of HCG or LH surge (r = 0.37, P < 0.001)but was unrelated to oestradiol level on the day of HCG administrationor LH surge (r = 0.12). Biochemical pregnancies were relatedto endometrial pattern (r = – 0.22, P = 0.02) but wereunrelated to maternal age or previous abortions. Clinical abortionswere related to age (r = 0.26, P = 0.01) and to previous abortion(r = 0.25, P = 0.013) but were unrelated to endometrial pattern.Neither biochemical pregnancy nor clinical abortion was relatedto oestradiol or LH levels on the day of HCG administrationor LH surge. These findings suggest that the majority of biochemicalpregnancies do not result from karyotypically abnormal embryos,as do clinical abortions.     

Effect of gonadotrophin-releasing hormone and related analogue on human luteal cell function in vitro

The possible direct effect of gonadotrophin-releasing hormone(GnRH) and GnRH agonist (GnRH-A; buserelin) on basal and humanchorionic gonadotrophin (HCG)-stimulated progesterone (P) andcyclic AMP (cAMP) production by cultured human luteal cellswas examined. Luteal cells from the early or mid-luteal phasewere incubated in long-term cultures. They responded to HCGstimulation with a 2- to 3-fold increase in P production anda 2-fold increase in cAMP production. The addition of GnRH (10^–7and 10^–5 M) or GnRH-A (10^–7 and 10^–5 M) tothe medium had no effect on either basal or HCG-stimulated secretion.These results indicate that both GnRH and GnRH-A have no directeffect on human luteal steroidogenesis in vitro.