Initiation of periovulatory events in gonadotrophin-stimulated macaques with varying doses of recombinant human chorionic gonadotrophin

During in-vitro fertilization (IVF) cycles, a large bolus of human chorionic gonadotrophin (HCG) is used to induce periovulatory events, but the efficacy of lower doses is undefined. Following follicular stimulation in rhesus monkeys, oocyte nuclear maturation, IVF, granulosa cell luteinization and corpus luteum function were compared after injection of 100, 300 or 1000 IU recombinant HCG or 1000 IU urinary HCG. Bioactive HCG rose to peak concentrations within 2 h that were proportional to the dose administered (100 < 300 < 1000 IU, recombinant HCG = urinary HCG). The duration of surge values (>100 ng/ml) was also dose-dependent (0 h, 100 IU; 24 h, 300 IU; >48 h, 1000 IU, recombinant and urinary HCG). While the proportions of oocytes resuming meiosis and undergoing IVF were similar among groups, fewer animals yielded fertilizable oocytes following 100 and 300 IU (five of nine) compared to 1000 IU recombinant and urinary HCG (nine of 10). Peak values of serum progesterone in the luteal phase were similar, but declined 2 days earlier after 100 and 300 IU relative to 1000 IU recombinant and urinary HCG. Thus, 3-10 fold lower doses of HCG elicit low amplitude surges of short duration that induce periovulatory events such as re-initiation of oocyte meiosis and granulosa cell luteinization. However, oocyte fertilization and luteal function may optimally require surges of higher amplitude and longer duration similar to those produced by standard doses of 1000 IU recombinant or urinary HCG.     

Effects of different test conditions on MICs of food animal growth-promoting antibacterial agents for enterococci

To examine whether luteal phase defect is, in part, causally related to insufficient gonadotrophin stimulation, we compared the relation of the increment of serum progesterone concentrations in response to human chorionic gonadotrophin (HCG) with its basal level at mid-luteal phase. Thirty-eight naturally cycling infertile women aged between 27-41 years old were evaluated for hormonal responses to HCG injection at the mid-luteal phase. We measured luteinizing hormone (LH), follicle stimulating hormone (FSH), oestradiol and progesterone concentrations, before and 1, 2 and 3 h after the administration of HCG (5000 IU, i.m.) 7 days after ovulation verified by ultrasonography. Eleven out of 38 women exhibited progesterone concentrations below 10 ng/ml (low progesterone group), and those remaining showed progesterone concentrations of > or = 10 ng/ml (normal progesterone group). The basal LH, FSH and oestradiol concentrations were essentially the same in both groups. Progesterone concentrations rose significantly 1 h after the injection and levelled off thereafter. The increment of progesterone concentrations at 1 h in the normal progesterone group was 5.7 ng/ml on the average, whereas that in low progesterone group was 1.1 ng/ml. Furthermore, the percentage increase in progesterone concentrations at 1 h in the normal progesterone group was significantly greater than that in the low progesterone group. Both groups equally exhibited significant but marginal increases in oestradiol concentrations 1 h after the injection. LH and FSH concentrations at 3 h decreased significantly in both groups. In summary, HCG readily stimulates progesterone production in normally functioning corpus luteum whereas its stimulatory effect is minimal on malfunctioning corpus luteum. This suggests that luteal phase defect is not caused by inadequate gonadotrophin stimulation and, therefore, does not benefit from HCG administration.     

Steroidogenesis in luteinized granulosa cell cultures varies with follicular priming regimen

During follicular development, a co-ordinated gonadotrophin and endocrine environment is believed to be essential for normal function of the resulting corpus luteum. Whether differences in the gonadotrophins used to promote follicular development can have lasting effects on granulosa cells after they have undergone luteinization and culture, remains to be studied. We measured steroid production under basal and human chorionic gonadotrophin (HCG) stimulation in short and long term cultures of luteinizing granulosa cells obtained from normal ovulatory women undergoing assisted folliculogenesis with either human menopausal gonadotrophin (HMG) or follicle stimulating hormone (FSH). Basal progesterone and oestradiol production by luteinized granulosa cells obtained from follicles stimulated to develop with FSH was significantly greater than that from HMG derived follicles (P < 0.001). In short term cultures, treatment with 10 IU HCG caused a 10-fold increase in progesterone release by cells from FSH stimulated follicles, whereas cells of HMG origin produced only 5-fold more progesterone (P < 0.0001). In cultures that were maintained for 2 weeks, progesterone secretion was reduced, but a similar trend in HCG responsiveness was observed. These experiments demonstrate that the composition of the gonadotrophins used to promote follicular development in vivo leads to differences in granulosa cell steroidogenesis which are evident after luteinization and culture. They additionally support the notion that the environment of follicular development will be reflected in the resulting corpus luteum.     

Follicle-stimulating hormone and luteinizing hormone/chorionic gonadotropin stimulation of vascular endothelial growth factor production by macaque granulosa cells from pre- and periovulatory follicles

Granulosa cells in the ovulatory follicle express messenger ribonucleic acid encoding vascular endothelial growth factor (VEGF), an agent that may mediate the neovascularization of the developing corpus luteum, but it is not known whether luteinizing granulosa cells synthesize and secrete VEGF during the periovulatory interval. Studies were designed to evaluate the effects of an in vivo gonadotropin surge on VEGF production by macaque granulosa cells (study 1) and to test the hypothesis that gonadotropins act directly on granulosa cells to regulate VEGF production (study 2). Monkeys received a regimen of exogenous gonadotropins to promote the development of multiple preovulatory follicles. Nonluteinized granulosa cells (i.e. preovulatory; NLGC) and luteinized granulosa cells (i.e. periovulatory; LGC) were aspirated from follicles before and 27 h after an ovulatory gonadotropin bolus, respectively. Cells were either incubated for 24 h in medium with or without 100 ng/mL hCG (study 1) or cultured for 6 days in medium with or without 100 ng/mL hCG or 0.1, 1, 10, and 100 ng/mL of recombinant human LH (r-hLH) or r-hFSH (study 2). Culture medium was assayed for VEGF and progesterone. In study 1, LGC produced 8-fold greater levels of VEGF than NLGC (899 +/- 471 vs. 111 +/- 26 pg/mL, mean +/- SEM; P < 0.05). In vitro treatment with hCG increased (P < 0.05) VEGF production by NLGC to levels that were not different from the LGC incubated under control conditions. In vivo bolus doses of r-hCG (100 and 1000 IU) and r-hFSH (2500 IU) were equally effective in elevating granulosa cell VEGF production. In study 2, in vitro treatment with r-hFSH, r-hLH, and hCG markedly increased (P < 0.05) VEGF and progesterone production by the NLGC in a dose- and time-dependent manner. By comparison, the three gonadotropins (100 ng/mL dose) only modestly increased VEGF and progesterone production by LGC. These experiments demonstrate a novel role for the midcycle surge of gonadotropin (LH/CG or FSH) in primates to promote VEGF production by granulosa cells in the periovulatory follicle. Further, the data demonstrate that FSH-like as well as LH-like gonadotropins directly stimulate VEGF synthesis by granulosa cells.     

Postnatal development of Leydig cells in the opossum (Monodelphis domestica): an immunocytochemical and endocrinological study

Using a mouse early preantral follicle culture system, mature full grown oocytes, arrested in prophase I of meiosis, were produced after 12 days using a recombinant gonadotrophin-supplemented medium. This culture medium does not mimic the normal extracellular environment of the oocyte and might therefore modify meiotic regulation and more particularly progression to metaphase II (MII). The aim of this study was to optimize the treatment using recombinant stimulatory ligands which were known to induce germinal vesicle breakdown (GVBD) and completion of meiosis I, metaphase II (MII), namely recombinant follicle stimulating hormone (r-FSH), chorionic gonadotrophin (r-HCG) and epidermal growth factor (EGF). Full-grown intrafollicular oocytes could not resume meiosis when the 'ovulatory' stimulus was r-FSH, used at a 100 times higher dose than during culture. r-FSH did not increase progesterone production. When 1.5 IU/ml r-HCG was used as meiotic trigger, germinal vesicle breakdown was obtained in 95% of the oocytes 64% of which extruded a first polar body. r-HCG induced a dramatic increase in progesterone production. When EGF was administered as sole stimulus on day 12 to the attached follicle-enclosed oocytes, only doses > or =5 ng/ml could cause GVBD, although less effectively than r-HCG (45 versus 95%; P < 0.0001). Oocytes undergoing GVBD by the EGF pulse reached metaphase II at a rate of 54% (not significant versus r-HCG). EGF did not stimulate progesterone production. Addition of increasing doses of EGF (0.5; 5; 10; 50 ng/ml) to r-HCG did not increase the GVBD-rate, but EGF doses >5 ng/ml improved MI to MII transition (P=0.027), thereby improving the final yield of MII oocytes by 12.5%. These data show that up to a dose of 50 ng/ml, EGF on its own could only override the somatic inhibitory stimuli in less than half of the cultured follicles. However, in addition to HCG, EGF (25 ng/ml) had a stimulatory effect on completing the first meiotic division. It was concluded that, under the present culture conditions, EGF in combination with HCG provided optimal nuclear maturation.     

Induction of ovulation in rabbits by pure urinary luteinizing hormone

In 18-week-old nulliparous rabbit does, ovulation was induced with 50 IU of pure urinary luteinizing hormone (LH; LH group), or 50 IU of human chorionic gonadotrophin (HCG; HCG group), in order to determine the effect of these treatments on 17 beta-oestradiol and progesterone concentrations, and on oocyte and embryo quality. Luteinizing follicles, recovered oocytes, progesterone concentration and grade 5 embryos were significantly reduced when pure urinary LH was used. Statistically significant correlations were found: (i) between oestradiol concentration and number of degenerated oocytes in both groups (positive); (ii) between oestradiol concentration and grade 1 and 2 embryos (negative), and grade 5 embryos (positive) in the HCG group; (iii) between progesterone concentration and metaphase II oocytes (negative), and between progesterone and grade 5 embryos (positive), in the HCG group; and (iv) between progesterone and oestradiol concentrations (negative) in the LH group. It seems that the oestradiol to progesterone ratio improves during the early luteal phase when ovulation is induced with LH, and that oestradiol and progesterone concentrations could play a role in determining oocyte and embryo quality.     

Immunohistochemical localization of the LH/HCG receptor in human ovary: HCG enhances cell surface expression of LH/HCG receptor on luteinizing granulosa cells in vitro

We examined the immunohistochemical localization of luteinizing hormone (LH)/human chorionic gonadotrophin (HCG) receptor (LH-R) in the human ovary using the anti-human LH-R monoclonal antibody, 3B5. In the antral follicles, LH-R was detected on theca interna cells. In pre-ovulatory follicles, granulosa cells also expressed LH-R. During corpus luteum formation, granulosa cells seemed to increase the expression of LH-R, and in corpus luteum of mid-luteal phase, large luteal cells expressed LH-R more intensely than small luteal cells. In the regressing corpus luteum, LH-R was almost undetectable on both luteal cells, whereas in the corpus luteum of early pregnancy, LH-R continued to be expressed on large luteal cells. The granulosa cells obtained from the patients undergoing in-vitro fertilization therapy were cultured for 3 days in serum-free medium, without or with HCG (10 IU/ml) and tumour necrosis factor (TNF)alpha (10 ng/ml). Flow cytometry showed that the expression of LH-R on the cell surface of luteinizing granulosa cells was enhanced by HCG, but was unaffected by TNFalpha. These results suggest that the main target cells for LH/HCG change from theca interna cells/small luteal cells to granulosa cells/large luteal cells during ovulation, corpus luteum formation, and differentiation into the corpus luteum of pregnancy, probably under the influence of LH/HCG.     

Follicle stimulating hormone alone supports follicle growth and oocyte development in gonadotrophin-releasing hormone antagonist-treated monkeys

Both follicle stimulating hormone (FSH) and luteinizing hormone (LH) are proposed requirements for follicular growth and steroidogenesis; however, the role of LH in primate folliculogenesis is unclear. Follicular stimulation by recombinant human FSH (n = 5) with and without recombinant LH (1:1; n = 6) following 90 days of gonadotrophin-releasing hormone (GnRH) antagonist (Antide) treatment in macaques was evaluated. Human chorionic gonadotrophin (HCG) was administered when six follicles > or = 4 mm were observed. Oocytes were aspirated 27 h later and inseminated in vitro. Chronic Antide reduced serum oestradiol and bioactive LH to concentrations observed in hypophysectomized rhesus monkeys. Multiple follicular growth required a longer interval following recombinant FSH (12 +/- 1 days) than recombinant FSH+recombinant LH (9 +/- 0.2 days), but the total number of follicles/animal did not differ between groups. The day prior to HCG, oestradiol concentrations were 4-fold less following recombinant FSH compared to recombinant FSH+recombinant LH. With recombinant FSH, more oocytes completed meiosis to metaphase II (51%) and fertilized (89 +/- 5%) relative to recombinant FSH+recombinant LH (12 and 52 +/- 11% respectively). Follicular growth and maturation in LH-deficient macaques occurred with FSH alone. Thus, LH is not required for folliculogenesis in primates. Higher fertilization rates following follicular stimulation with FSH alone suggest that the presence of LH with FSH (1:1) during the pre-ovulatory interval impairs gametogenic events in the periovulatory period.     

Differential responses of granulosa cells from small and large follicles to follicle stimulating hormone (FSH) during the menstrual cycle and acyclicity: effects of tumour necrosis factor-alpha

This study determined effects of follicle stimulating hormone (FSH) alone and in combination with tumour necrosis factor (TNF), on granulosa cells from small (5-10 mm diameter) and large (>10-25 mm) follicles during follicular and luteal phases of the cycle and during periods of acyclicity. Granulosa cells were collected from ovaries of premenopausal women undergoing oophorectomy. The cells were cultured with human FSH (2 ng/ml) and testosterone (1 microM) in the presence or absence of human TNF-alpha (20 ng/ml). Media were removed at 48 and 96 h after culture and progesterone, oestradiol and cAMP in media were measured by radioimmunoassays. FSH stimulated the accumulation of oestradiol from granulosa cells of small follicles during the follicular and luteal phases but not during acyclicity; and TNF reduced oestradiol accumulation in the presence of FSH. Interestingly, in granulosa cells from small follicles, progesterone and cAMP secretion increased in response to FSH and neither was affected by TNF. Thus, TNF specifically inhibited the conversion of testosterone to oestradiol in granulosa cells from small follicles. FSH stimulated oestradiol production by granulosa cells of large follicles obtained only during the follicular phase of the cycle and TNF inhibited the FSH-induced oestradiol secretion. Granulosa cells obtained from large follicles during the luteal phase and during acyclicity did not accumulate oestradiol in response to FSH. However, FSH increased progesterone and cAMP secretion by granulosa cells obtained from large follicles during the follicular and luteal phases. During the luteal phase alone, TNF in combination with FSH increased progesterone accumulation above that of FSH alone. FSH did not increase progesterone, oestradiol or cAMP secretion by granulosa cells obtained from large follicles during acyclicity. Thus, FSH increases progesterone, oestradiol and cAMP secretion by granulosa cells of small follicles during the follicular and luteal phases and TNF appears to inhibit FSH-induced oestradiol secretion specifically in those cells. In large follicles, FSH-stimulated granulosa cell secretion of oestradiol is limited to the follicular phase and this effect can be inhibited by TNF. In addition, when granulosa cells of large follicles do not increase oestradiol secretion in response to FSH, TNF stimulates progesterone secretion.     

Daily measurements and in-vitro effects of human chorionic gonadotrophin in the early luteal phase

The purpose of the present study was to analyse daily measurements of human chorionic gonadotrophin (HCG) in in-vitro fertilization (IVF) cycles and to reproduce the effects of HCG in vitro using human granulosa-luteinized cells from the same patients. The study population consisted of nine women undergoing IVF because of tubal infertility in whom blood was drawn every 24 h from the day of the ovulatory dose of HCG (10,000 IU) until 6 days after ovum pick-up. Granulosa-luteal cells from the follicular aspirates were collected and cultured in vitro up to 6 days in the presence of increasing concentrations (0, 0.01, 0.1, 1.0 and 100.0 IU/ml) of HCG. Serum progesterone and HCG in vivo as well as progesterone accumulation in vitro on days 2, 4 and 6, were the main outcome measures. Maximum HCG concentrations (0.25 IU/ml) were reached the day before ovum pick-up, and continuously decreased until day 6 after ovum retrieval. HCG did not stimulate progesterone production in vitro at any dose tested until day 6 after ovum pick-up. Then, 0.01 IU/ml resulted significantly (P < 0.05) stimulatory compared to controls, while 1.0 IU/ml was inhibitory (P < 0.05). It is concluded that HCG supplementation in an IVF cycle is unnecessary until day 6 after ovum pick-up. On day 6, progesterone production is stimulated with very low concentrations of HCG.     

Dietary fat and body composition

Vascular endothelial growth factor (VEGF) is a cytokine that induces angiogenesis. Angiogenesis is a prominent histologic component of the luteinization process. Luteinization is also characterized by granulosa cell progesterone secretion in response to the luteinizing hormone (LH) surge. Local VEGF production in human pre-ovulatory follicles, induced by LH, was postulated to be a luteinization mediator in women. To investigate this hypothesis, serum and fluid from the dominant follicle of 31 healthy regularly cycling multiparous women undergoing laparoscopic sterilization were obtained. VEGF was measured by enzyme-linked immunosorbent assay, and LH and progesterone were measured by radioimmunoassay. Follicle aspiration was performed at a median of 13 days from the last menstrual period (range 11-17 days). The median pre-ovulatory follicle diameter was 16 mm (range 11-23 mm). Follicle fluid VEGF concentrations (mean 6900 pg/ml, range 1200-17 100 pg/ml) were correlated positively with follicle fluid progesterone concentrations (mean 10 176 nmol/l, range 636-66780 nmol/l, r=0.62, P=0.002). This correlation was even tighter (r=0.87, P < 0.0001) when only samples from the 22 women in the earliest stages of follicle luteinization were considered. In these women serum LH concentrations were also correlated with follicle fluid VEGF concentrations (r=0.51, P=0.02). Our findings demonstrate the close dynamic relationship between VEGF production and early luteinization in human follicles during normal non-stimulated cycles.     

Evidence suggesting an additional control mechanism regulating episodic secretion of luteinizing hormone and follicle stimulating hormone in pre-pubertal children and post-menopausal women

The possible differential regulation of pulsatile follicle stimulating hormone (FSH) and luteinizing hormone (LH) secretion in pre-pubertal children and in post-menopausal women was investigated. Children were studied for 4 h and post-menopausal women for 6 h; blood samples were taken every 10 min. Post-menopausal women were studied before and 21 days after administration of a single i.m. dose of gonadotrophin-releasing hormone (GnRH) analogue. Eight post-menopausal women and 18 children (nine boys and nine girls) were enrolled. The children were divided into two groups: A, at Tanner stages 0-1 (four boys and three girls); B, at Tanner stage 2-3 (five boys and six girls). Plasma LH and FSH concentrations were determined using an immunofluorimetric assay. Time series were analysed and the specific concordance (SC) index was computed to determine the degree of concordance between episodes of LH and FSH secretion. While children of group A had LH concentrations below the minimal detectable dose of 0.1 IU/l, group B showed measurable LH plasma concentrations (1.4 +/- 0.3 IU/l, mean +/- SEM). Plasma FSH concentrations were detectable in both groups. Group A showed FSH plasma concentrations significantly lower than those of group B (0.75 +/- 0.2 and 1.95 +/- 0.4 IU/l respectively; P < 0.05), but FSH pulse frequency was higher in group A (P < 0.05). Children of group B showed significant concomitance of LH and FSH secretory events at time 0 (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Sequential step-up and step-down dose regimen: an alternative method for ovulation induction with follicle-stimulating hormone in polycystic ovarian syndrome

This study was designed to compare both the effectiveness and safety of two low-dose gonadotrophin regimens (step-up versus sequential step-up and step-down) for ovulation induction in polycystic ovarian syndrome (PCOS) patients. In all, 56 infertile clomiphene citrate-resistant PCOS patients were included in this prospective randomized study. A total of 38 cycles were conducted with a classic step-up protocol, whereas for 35 cycles the follicle-stimulating hormone (FSH) threshold dose was reduced by half when the leading follicle reached 14 mm in diameter (sequential protocol). Serum oestradiol, progesterone and luteinizing hormone concentrations and follicular growth rate were evaluated during the cycle. At the time of human chorionic gonadotrophin administration, cycles treated with sequential protocol exhibited significantly lower oestradiol concentrations [434 +/- 45 versus 593 +/- 67 pg/ml (mean +/- SEM)] and the number of medium-sized (14-15 mm) follicles was significantly reduced (0.3 +/- 0.1 versus 0.8 +/- 0.2) compared with cycles treated with the classic step-up protocol. Moreover, in these cycles serum luteal oestradiol concentrations were decreased significantly (350 +/- 77 versus 657 +/- 104 pg/ ml) compared with the classic step-up protocol. A sequential step-up and step-down protocol seems to be a safe and effective regimen for ovulation induction in PCOS patients. Decreasing the FSH dose following step-up follicular selection may be an alternative method to avoid multifollicular development.     

Recessive Robinow syndrome: with emphasis on endocrine functions

We present the characteristic features of 14 children with the recessive form of Robinow syndrome and the growth hormone (GH) response to provocation with clonidine and the serum insulin-like growth factor-I (IGF-I) concentration in 12 of these children. The gonadotropin (luteinizing hormone [LH] and follicle-stimulating hormone [FSH]) response to gonadotropin-releasing hormone (GnRH) was evaluated in early pubertal and pubertal patients, and the testosterone response to human chorionic gonadotropin (HCG) was evaluated in males. Children with Robinow syndrome, born at full-term, were short at birth (length, 41.4+/-2.1 cm) and had markedly slow growth velocity (GV) during the first year (13.1+/-2.1 cm/yr); consequently, they were significantly short at the end of the first year of life (length, 54.4+/-2.9 cm). This intrauterine and early extrauterine growth delay reflected low growth potential. During childhood, the GV standard deviation score (GVSDS) remained low (-2.17+/-0.83). Despite the presence of empty sella in all of the patients, they had an adequate GH response to clonidine provocation (peak, 19.3+/-5.8 microg/L) and a normal serum IGF-I concentration (309+/-142 ng/mL) for their age. During childhood and early adolescence, boys with Robinow syndrome had low basal testosterone and a low testosterone response to HCG stimulation (3,000 IU/m2/d intramuscularly [IM] for 3 days). However, their basal and GnRH-stimulated FSH concentrations were normal. Two girls (Tanner II breast development) had a normal serum estradiol (E2) concentration but high LH and FSH responses to GnRH stimulation. This suggested either defective feedback of E2 on the hypothalamic-pituitary axis or hyporesponsiveness of the ovaries to gonadotropin. Four weeks of HCG therapy (2,500 IU/m2 IM twice weekly) in three boys with Robinow syndrome increased the penile length and testicular volume, denoting a significant Leydig cell response to prolonged HCG stimulation and the presence of functioning androgen receptors. It is suggested that HCG and/or testosterone therapy during infancy may improve the severe micropenis in these patients.     

Enhanced bradycardia induced by beta-adrenoceptor antagonists in rats pretreated with isoniazid

Recent studies indicate that the midcycle gonadotropin surge in the human occurs without an increase in hypothalamic gonadotropin-releasing hormone (GnRH) pulse frequency. In addition, previous studies employing a GnRH antagonist to provide a semiquantitative estimate of endogenous GnRH secretion suggest that the overall amount of GnRH secreted is decreased at the time of the surge. To investigate the hypothesis that a normal gonadotropin surge can be generated in the human with a decreased amount of GnRH at the midcycle, 7 GnRH-deficient subjects underwent two cycles of a physiologic regimen of intravenous pulsatile GnRH therapy. In the control cycle, 75 ng/kg/bolus of GnRH, a dose known to be sufficient for folliculogenesis, was administered throughout the cycle, using physiological frequencies. In a second cycle, the bolus dose of GnRH was decreased by one-half log order to 25 ng/kg just prior to the luteinizing hormone surge and returned to 75 ng/kg after documented ovulation. All cycles were ovulatory. The peak luteinizing hormone level (77.4 +/- 9.7 vs. 67.5 +/- 17.6 IU/l) did not differ between the control and decreased GnRH cycles. There was no difference in the peak serum estradiol level (475.8 +/- 144.1 vs. 493.2 +/- 93.0 pg/ml), follicular phase length (15.0 +/- 1.3 vs. 14.8 +/- 0.6 days), or progesterone level (22.4 +/- 5.1 vs. 34.8 +/- 5.7 ng/mg) on day 6 of the luteal phase in the control and decreased GnRH cycles, respectively. Three pregnancies were achieved in each of the control and reduced GnRH cycles. We conclude that a decreased overall amount of GnRH generates a normal midcycle gonadotropin surge and has no significant impact on luteal phase adequacy or fertility. These results provide further evidence that a decrease in endogenous hypothalamic GnRH secretion may occur at the midcycle in normal women. This study also provides evidence that the GnRH requirements for normal follicular and luteal phase dynamics may well be greater than those required for generation of a normal midcycle gonadotropin surge and ovulation in women.     

Examination of the role of FSH in periovulatory events in the hamster

The need for endogenous FSH in the periovulatory events such as oocyte maturation, ovulation, luteinization, maintenance of luteal function and follicular maturation was examined in the cyclic hamster. A specific antiserum to ovine FSH, shown to be free of antibodies to LH and to cross-react with FSH of the hamster, was used to neutralize endogenous FHS at various times. Administration of this antiserum during pro-oestrus did not affect oocyte maturation and ovulation, as judged by the normality of the ova to undergo fertilization and normal implantation. It also had no effect on the process of luteinization or on the maintenance of luteal function as indicated by the normal levels of plasma and luteal progesterone during pro-oestrus and oestrus during the cycle and in pregnancy. All these processes were, however, disrupted by administration of an antiserum to ovine LH, thereby demonstrating their dependence on endogenous LH. Although FSH antiserum given at pro-oestrus did not prevent the imminent ovulation, it blocked the ovulation occurring at oestrus of the next cycle. This antiserum was effective in preventing the ensuing ovulation when given at any other time of the cycle until the morning of pro-oestrus. It is concluded that, in the hamster, high levels of FSH during pro-oestrus and oestrus are required for initiating maturation of a new set of follicles which are dependent on the trophic support of FSH throughout the cycle until the morning of pro-oestrus. Such follicles then appear to need only LH for subsequent ovulatory and associated processes.     

Influence of serum, estrogen, and gonadotropins upon growth and progesterone secretion by cultures of granulosa cells from small porcine follicles

Granulosa cells from small (less than 2mm) antral porcine follicles were grown in culture to study the effects of various hormones on growth, morphology and progesterone secretion. Culture medium 199D + 4% serum was found to be most suitable since it maintained a fairly constant cell population. Estradiol (1mug/ml) and human FSH stimulated cell growth. LH and FSH stimulated progesterone secretion and induced morphological changes associated with luteinization. Estradiol (0.1 mug/ml) inhibited progesterone secretion by granulosa cells.