Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “FSH”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,189 records · Page 66Linked to original sources
PubMed1988

[A longitudinal study on the prognosis of ovulatory disturbance in teenage patients with high LH and normal FSH serum levels].

To study the prognosis of adolescent ovulatory disturbance in patients with persistently elevated LH levels (greater than or equal to 25 mIU/ml), normal FSH levels and high LH/FSH (greater than 2.0), 17 patients aged 12-19 years were studied longitudinally for 4-9 years. These 17 patients consisted of 7 patients suffering from amenorrhea with estrogenic effect, 5 patients with functional bleeding, 3 patients with delayed menarche and 2 patients with oligomenorrhea. All of the patients showed exaggerated LH responses to 100 micrograms of LHRH administration while the FSH responses were not different from those obtained from normal women. Out of the 17 patients, 10 (58.8%) patients showed the values of testosterone and 7 (41.2%) androstenedione which were above the mean + 2SD of normal women. Consequently, the mean serum testosterone and androstenedione levels were significantly higher than those in normal women. The mean LH (36.6 +/- 8.3 mIU/ml), FSH (11.2 +/- 1.5 mIU/ml) and LH/FSH (3.3 +/- 0.8) at the age of 21.4 +/- 2.5 years were not different from the mean LH (39.9 +/- 13.3 mIU/ml), FSH (10.8 +/- 1.8 mIU/ml) and LH/FSH (3.8 +/- 1.5) at the age of 16.1 +/- 1.8 years, respectively. None of the 17 patients showed amelioration or deterioration of ovulatory disturbance during long-term observation. To further investigate the central dopamine activity, 10 mg of metoclopramide (MCP) was administered intravenously in these 17 patients. The LH and PRL responses to MCP were evaluated, and the results were compared to those obtained from 17 patients aged over 20 with PCO and from 17 normal women. The LH responses to MCP were positive in this juvenile patient group and the patients aged over 20 PCO group. However, the LH responses to MCP were negative in normal women in both the follicular and luteal phases. In contrast, the PRL responses to MCP were significantly attenuated in juvenile patients and in patients aged over 20 with PCO compared to those in normal women. Since the hormonal profiles in these 17 patients with anovulation or oligo-ovulation were very similar to those in the group aged over 20 with established PCO, it may be suggested that 1) at least part of the adult patients with PCO may have had PCO from late adolescence; 2) the majority of the patients with high LH and normal FSH levels in adolescence will suffer from ovulatory disturbance continuously; 3) in these patients, an aberration of central dopamine in control of LH and PRL may exist.

Adolescent↗
PubMed1990

[Determination of the normal range of serum LH and FSH levels in normal adult males--comparison with IRMA and RIA].

To determine the normal range of serum LH and FSH levels, blood samples from 53 normal adult males were measured by a double antibody radioimmunoassay system and a new immunoradiometric assay (IRMA) system. It was necessary to evaluate the individual pulsatile secretion and the differences in measured values among laboratories to determine the normal range. Therefore, in 53 normal adult males lacking any evidence of hormonal abnormalities, blood was sampled at 9:00 a.m. daily for 3 days, and these samples were measured in 3 laboratories. The result of the hormone concentration of blood sample was not appropriate as the normal range because of the high amplitude of LH and FSH pulses. Coefficient values (CV) between the mean value of the first two samples and the mean value of all three samples were small. Therefore, the mean value of the first two samples was clinically accurate for use as the normal range. Significant differences in measured values were observed among the 3 laboratories. The normal range, which included individual pulsatile secretion, and the differences in measured values among the laboratories was as followings: LH (RIA): 7.6-13.7 mIU/ml, LH (IRMA): 2.1-4.7 mIU/ml, FSH (RIA): 4.7-9.5 mIU/ml, FSH (IRMA): 3.0-7.4 mIU/ml. The serum LH and FSH levels of 68 untreated male infertility patients tended to rate high with respect to our normal range. It was considered that the normal range determined in this study was useful for clinical management.

Adult↗
PubMed1975

LH and FSH in serum after intramuscular administration of LH/FSH-releasing hormone in normal and hypogonadal men.

The increase in serum concentrations of LH and FSH after intramuscular administration of LH/FSH-RH was investigated in normal and hypogonadotrophic hypogonadal males. LH and FSH were measured by specific radio-immunoassays. To evaluate the appropriate dose of LH/FSH-RH for intramuscular administration different doses were administered and with 200 mu g an increase in LH and FSH was found comparable to the results obtained by other investigators using intravenous administration. After the initial studies a simple test including two determinations before LH/FSH-RH administration and one 60 min and 120 min after administration was developed and used in all cases. In 12 normal males a significant increase in the serum concentration of both LH and FSH was found averaging 381% and 148% respectively 60 min after 200 mu g LH/FSH-RH with a slight decrease in LH but not in FSH after 120 min. A positive response similar to that in normal men was observed in 11 hypogonadotrophic hypogonadal patients presenting different clinical pictures. This indicates that in all these patients the hypogonadotrophic state was due to a hypothalamic defect and not to a hypophyseal disorder.

17-Ketosteroids↗
PubMed1975

Affinity and specificity of antisera against human FSH and TSH obtained by immunizing rabbits with highly purified hormone preparations.

Two groups of 4 rabbits were immunized according to the method described by Vaitukaitis et al. (1971). One group was given 55 mu g (900 IU) FSH/animal and the other 100 mu g (o.5 IU) TSH/animal. Two highly specific antisera against FSH and one specific antiserum against TSH were obtained. The FSH antisera showed affinities towards LH and TSH of 0.13 and 0.25% respectively as compared to that of FSH. The TSH antisera showed affinities towards LH and FSH of 2.2 and 1.7% respectively as compared to that of TSH. The specific antisera showed no or minor affinities towards the LH-alpha subunit and they were sufficient specific to be used in the radioimmunoassay of serum from pregnant women without pre-absorption with HCG. Scatchard plots showed the association constants of the FSH antisera to be 1.3 times 10-11 and 1.2 times 10-11 1/mol respectively, and the association constant of the TSH antiserum to be 6 times 10-10 1/mol. All 3 antisera showed high titers.

Animals↗
PubMed1978

Cyclic AMP and cyclic GMP accumulation in hamster pre-ovulatory follicles stimulated with LH and FSH.

Cyclic AMP and cyclic GMP accumulation in hamster pre-ovulatory follicles was determined after in vitro stimulation by LH and FSH. Combined time course and dose response experiments determined that the acute response of the follicles (0-30 min) to LH and FSH was similar with respect to cyclic AMP accumulation. The pattern of cyclic GMP accumulation was, however, distinctly different in LH and FSH stimulated follicles. LH increased follicular cyclic GMP only at the lowest dose (0.005 IU/ml), while higher doses of LH had no effect. In contrast, FSH at all doses stimulated cyclic GMP accumulation. The different cyclic AMP to cyclic relationships generated in the follicles by LH and FSH may be determinants in specificity of hormone action in pre-ovulatory follicles.

Animals↗
PubMed1980

Precocious and delayed puberty. Studies of FSH and LH production and metabolism.

We measured the production rates and metabolic clearance, disappearance and excretion rates of FSH and LH as well as plasma testosterone and delta 4-androstenedione in males with precocious and delayed puberty. In precocious puberty, we found modestly elevated FSH production early in puberty, reaching adult levels by midpuberty and remaining constant thereafter. LH production was low early in puberty, reached high levels at midpuberty and then fell. The plasma testosterone concentrations paralleled the changes in LH. This suggests that moderate FSH production is achieved by early puberty and adult levels are reached by midpuberty. On the other hand LH production is low early in puberty, reaches high levels by midpuberty and then falls again towards the end of puberty. Constitutional delay in sexual development probably consists of several syndromes due either to a delay in LH production or to FSH production or to both. One patient with hypogonadotrophic hypogonadism was also studied. He showed relatively normal LH production but very low FSH production.

Adolescent↗
PubMed1986

Effect of clomiphene citrate on the in vitro release of LH and FSH by the pituitary gland of the long-term ovariectomized rat pretreated with LRH or with LRH and oestradiol benzoate.

The effect of a combined in vivo pre-treatment with luteinizing hormone-releasing hormone (LRH) and either oestradiol benzoate (OB), clomiphene (-citrate) or OB plus clomiphene on the autonomous and the supramaximally LRH-stimulated in vitro secretion of LH and FSH by pituitary glands of long-term ovariectomized (OVX) rats was studied using a hemipituitary perifusion system. The concentration of LRH in the perifusion medium was 1 microgram/ml. Pre-treatment with LRH during 5 days was effected by means of sc implanted Alzet osmotic minipumps; control rats received a piece of silastic with the dimensions of a minipump. OB, 3 micrograms/injection, clomiphene 100 micrograms/injection or solvent were given on days 2 and 4 (day of perifusion: day 5). In rats not pre-treated with LRH neither OB, nor clomiphene changed the content of the pituitary gonadotropin stores. There was only a small but significant positive effect of the combined treatment with OB and clomiphene on the pituitary FSH content. LRH (partly) depleted the gonadotropin stores. This effect of LRH was potentiated by OB, but not by clomiphene. Clomiphene prevented the depletion-potentiating effect of OB. OB raised the LRH-stimulated secretion of LH and FSH as well as the autonomous secretion of LH. Clomiphene raised the LRH-stimulated (not the autonomous) secretion of LH and FSH. OB plus clomiphene had the same effect as OB alone. Clomiphene also raised the LRH-stimulated secretion of LH and FSH after pre-treatment with LRH, but OB did not do so: LRH prevented the stimulatory effect of OB but not of clomiphene. OB plus clomiphene had the same effect as OB alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Sequential effects of FSH on the first stages of ovarian follicular development in normal and dwarf Snell mice.

The population of small growing ovarian follicles was divided into 4 classes according to the number of granulosa cells (from 15 to 95) surrounding the oocyte, and a comparison was made of normal and dwarf mice. Follicular cell proliferation was estimated by tritiated thymidine incorporation. In normal mice, most follicles in classes 1 (15 to 35 granulosa cells in their largest cross-section) and 2 (36 to 55 cells) were labelled (86 and 95%, respectively); FSH treatment increased the labelling index (L.I.) in all follicle classes. In dwarf mice, only 38 and 76% of follicles in classes 1 and 2, respectively, were labelled. However, FSH treatment increased the percentage of labelled follicles and the L.I. to levels which were similar to those in the ovaries of untreated, normal animals. FSH stimulation of the percentage of labelled follicles and L.I. was obvious as early as 3 h after injection. There was a major increase of the L.I. 24 h after FSH stimulation, specially in dwarf mice; several hypotheses are proposed to explain this finding. We conclude that FSH is necessary for the development of the population of small growing follicles in the mouse ovary.

Animals↗
PubMed1999

LH and FSH secretory responses to GnRH in normal individuals: a non-parametric deconvolution approach.

OBJECTIVE: To reconstruct the instantaneous secretion rate (ISR) of LH and FSH after GnRH administration in normal volunteers using non-parametric deconvolution, and to derive a direct integration formula to evaluate the amount of LH and FSH secreted during the first 60 min after the stimulus. DESIGN AND METHODS: First, the deconvolution method was validated in vivo by reconstructing doses ranging from 7.5 IU to 75 IU injected in three healthy adult volunteers whose endogenous LH had previously been downregulated by pretreating them, 3-4 weeks earlier, with 3.75 mg GnRH agonist i.m. Then, 40 healthy adult male volunteers were tested with a single 100 microg GnRH bolus, administered at 0 min. LH and FSH concentrations were determined at -30, 0, 15, 30, 45, 60, 90, and 120 min. RESULTS AND CONCLUSIONS: The validation study, conducted over a 10-fold range of doses, demonstrated that non-parametric deconvolution provided a reasonably accurate estimate of the amount of hormone entering the circulation. Applying deconvolution to the LH and FSH responses to GnRH, the ISRs of both hormones were shown to have a similar pattern, with a clearly delimited pulse after the GnRH bolus. In conjunction with earlier analyses of estimates of GHRH-stimulated GH secretion, we conclude that secretagogues evoke discrete LH, FSH, and GH secretory bursts of about 60 min total duration, despite markedly unequal (glyco-)protein hormone half-lives (18-500 min). With respect to the assessment of total hormone release during the first 60 min after the stimulus, the integration formula provided a reliable approximation of the result obtained by deconvolution, and had a negligible dependence on the samples at times 90 and 120 min.

Adult↗
PubMed2000

Inverse correlation between baseline inhibin B and FSH after stimulation with GnRH: a study of serum levels of inhibin A and B, pro alpha-C and activin A in women with ovulatory disturbances before and after stimulation with GnRH.

OBJECTIVE: Interest has focused recently on the influences of the polypeptide factors inhibin and activin on the selective regulation of the pituitary secretion of gonadotropins. DESIGN: Measurement of the concentrations of inhibin-related proteins in relation to the changes in pituitary gonadotropin (FSH, LH) parameters, after GnRH stimulation with a bolus injection of 100 microg gonadorelin, in 19 women with ovulatory disturbances. METHODS: Serum levels of inhibin A and B, activin A, and pro alpha-C were measured using sensitive ELISA kits. RESULTS: Within 60 min after GnRH stimulation, FSH values doubled from 5 to 10 mU/ml (P < 0.001). LH increased 12-fold from 2 to 24 mU/ml (P < 0.001). Activin A showed a significant decrease from 0.47 to 0.36 ng/ml (P < 0.001), whereas pro alpha-C increased from 127 to 156 pg/ml (P = 0.039). The median inhibin A concentration did not show a significant change between baseline and the 60 min value, whereas inhibin B was characterized by a minor, but not significant, increase in the median from 168 to 179 pg/ml (P = 0.408). A significant inverse correlation (P = 0.014) with a mean coefficient of correlation of 0.5516 was found, demonstrating a strong relationship between high inhibin B baseline levels and a small increase of FSH after 60 min. CONCLUSION: Our results show an interesting correlation between the baseline inhibin B and the change in FSH before and after GnRH stimulation. A high baseline inhibin B implies only a minor increase of FSH after 60 min.

Activins↗
PubMed2000

Serum concentrations of LH and FSH in the healthy newborn.

OBJECTIVE: A sex difference in fetal and neonatal pituitary-gonadal function has been well documented. The aim of the following study was to determine sex differences and patterns of basal LH/FSH in the neonatal period. DESIGN: Peripheral venous blood was obtained from 164 healthy full term newborns (91 males, 73 females) for clinically indicated laboratory examinations. RESULTS: In male newborns, LH values were initially low (days 1-5), increased between days 6 and 10, and reached maximum levels between days 16 and 20. Levels of FSH were initially low (days 1-5), increased between days 6 and 10 and reached maximum levels between days 11 and 15. In female newborns, LH levels were generally lower than in newborn boys; levels were initially low, then increased between days 11 and 15 and reached maximum levels at the end of the newborn period. FSH values were generally higher than in newborn boys; there were initially low values with a first peak between days 11 and 15 and a second peak between days 21 and 28. CONCLUSIONS: LH values in male newborns were higher and exceeded values in female newborns, whereas FSH values in female newborns exceeded male newborn values. Male newborns do not exhibit any peaks of LH and FSH activity, whereas female newborns exhibit two FSH peaks during this period.

Aging↗
PubMed2001

Effects of leptin on secretion of LH and FSH from primary cultured female rat pituitary cells.

BACKGROUND: Leptin, which is the product of the obese gene, is believed to play important roles in pubertal development and reproductive function in females. In a study using adult male rats, it was found that leptin stimulated secretion of gonadotropin from the pituitary in a dose-related manner. However, there has been no such study in female rats. OBJECTIVE: To investigate the effects of leptin on the production of LH and FSH from the pituitary in female rats, using primary cultured pituitary cells. METHODS: In this study, we determined body weight, serum leptin concentration and serum estradiol (E(2)) concentration in female Wistar rats at 3, 5, 6, 7, 9 and 11 weeks of age, and cultured pituitary cells from 6-week-old female Wistar rats with leptin (0--10(-7) mol/l) and GnRH (0 or 10(-8) mol/l). Then basal and GnRH-stimulated extra- and intracellular LH and FSH were assayed by RIA. RESULTS: Serum leptin concentration increased with increases in body weight and E(2) concentration. The pubertal serum leptin concentration was about 10(-10) mol/l. At a lower or moderate concentration, leptin produced dose-related increases in both basal and GnRH-stimulated extra- and intracellular LH and FSH in pituitary cells. At a concentration of 10 mol/l, leptin significantly (P<0.05) stimulated both basal and GnRH-stimulated extra- and intracellular LH and FSH. However, at greater concentrations, these effects diminished. CONCLUSIONS: These results indicated that leptin induced pituitary cells to produce and secrete both LH and FSH, with or without GnRH. The concentration of leptin that induced the greatest production of gonadotropins by pituitary cells was 10(-10) mol/l, which was the same as the physiological pubertal concentration. Leptin may be involved in the onset of puberty. It is also conceivable that leptin may be a cause of ovulatory failure, not only in weight loss but also in weight gain.

Animals↗
PubMed1979

Plasma concentrations of FSH and LH in entire and castrated prepubertal bull calves treated with Gn-RH.

In bulls there was no increase in plasma FSH and only a small increase in LH over the first 14 weeks of age. In steers (castrated) plasma LH and FSH were unchanged for the first 3 weeks but increased significantly at 7 and 14 weeks. After 100 micrograms Gn-RH, LH release in bulls was minimal until 7 and 14 weeks and there was no comparable rise for FSH. LH and FSH responded to Gn-RH throughout the trial in the steers. The neonatal calf testes selectively inhibited the release of FSH from the pituitary even when challenged with Gn-RH.

Animals↗
PubMed1985

Relationships between LH, FSH and prolactin secretion and reproductive activity in the weaned sow.

Blood samples were collected from primiparous sows via indwelling jugular cannulae at 15-min intervals for 12 h before and for 24 h (2 sows) or 48 h (10 sows) after weaning and then every 4 h until behavioural oestrus. Weaning to oestrus intervals ranged from 3 to 10 days and 2 sows showed no signs of oestrus and had not ovulated by Days 11 and 16 after weaning. Prolactin concentrations in plasma decreased significantly (P less than 0.001) and reached basal levels 1-2 h after weaning in all sows whilst plasma progesterone concentrations remained basal until approximately 30 h after the preovulatory LH surge in sows that ovulated. Elevated concentrations of prolactin or progesterone during the post-weaning period were, therefore, not responsible for delayed restoration of cyclicity. Overall, mean LH concentrations rose significantly (P less than 0.001) from 0.22 +/- 0.02 during the 12-h period before weaning to 0.38 +/- 0.03 ng/ml during the 12-h post-weaning period. After weaning, pulsatile and basal LH secretions were markedly increased for sows that showed an early return to oestrus (less than or equal to 4 days) compared with sows showing a longer weaning to oestrus interval but a correlation did not exist between either of these LH characteristics and the time taken to resume cyclicity. Mean LH concentrations before weaning were, however, inversely related (r = -0.649; P less than 0.05) to the weaning to oestrus interval. Overall, mean FSH concentrations rose significantly (P less than 0.001) from 151.1 +/- 6.2 (s.e.m.) ng/ml in the 12-h period immediately before weaning to 187.7 +/- 9.7 ng/ml in the subsequent 12-h period but there was no correlation between FSH concentrations, before or after weaning, and the interval from weaning to oestrus. However, a significant correlation was apparent between ovulation rate and peak concentrations of the rise in FSH after weaning (r = 0.746; P less than 0.05) and overall mean FSH values (r = 0.645; P less than 0.05). It is concluded that both LH and FSH concentrations in peripheral blood rose in response to removal of the suckling stimulus at weanling. The increase in LH pulse frequency associated with weaning was not directly related to the weaning to oestrus interval although a specific pattern of LH secretion was observed in sows showing an early return to oestrus (less than or equal to 4 days).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1985

Individual variations in FSH release after a GnRH challenge and relationship with semen output in young bulls.

Blood samples collected from 54 Montbéliarde young post-pubertal bulls were assayed for FSH. In the first trial, 0.25 mg GnRH was given to each of 25 bulls at 12 months of age. In a second group of 29 bulls, each received 20 mg dexamethasone followed by 0.25 mg GnRH 5 h later. Based on measurements of semen output, the bulls were classified into three categories: good, medium and poor semen producers. The total FSH response was significantly different among individuals (P less than 0.05) and repeatable (r = 0.45) only after the combined treatment. The mean total responses did not differ significantly between the 3 categories of semen producers, but individual FSH responses were significantly and negatively correlated to quantitative and qualitative semen production characteristics (r = 0.4-0.7). It was concluded that measurement of FSH after a combined dexamethasone-GnRH challenge permits the demonstration of a significant relationship between FSH release and semen production in individual bulls.

Animals↗
PubMed1987

Effect of photoperiod on LH, FSH and prolactin patterns in ovariectomized oestradiol-treated heifers.

Angus and Angus crossbred heifers were ovariectomized, treated with oestradiol implants and randomly assigned to the natural photoperiod of fall to spring for 43 degrees N latitude or extra light simulating the photoperiod of spring to fall. Weekly blood samples were taken for 6 months (fall to spring equinox). All heifers were cannulated every 4 weeks and blood samples were taken for 4 h at 15-min intervals. Sera were assayed for LH, FSH, prolactin and oestradiol. In samples taken weekly, serum LH and FSH concentrations were higher while serum prolactin was lower in heifers exposed to natural photoperiod. There was a photoperiod X time interaction for both FSH and prolactin with concentrations diverging as photoperiod diverged. Circulating concentrations of oestradiol were not different between groups. In samples taken every 4 weeks at 15-min intervals, baseline concentrations of LH and FSH and LH pulse amplitude were higher while prolactin pulse frequency was lower in heifers exposed to natural photoperiod. There was a photoperiod X time interaction for each of these pulsatile characteristics. The correlation between LH and prolactin concentrations estimated from the 15-min samples differed between the two photoperiod treatment groups. The pooled correlation coefficient (r) was -0.12 under natural photoperiod and +0.50 under extra light. There was also a photoperiod X time interaction with negative correlations occurring when photoperiod was decreasing and positive correlations occurring when photoperiod was increasing. These results support the hypothesis that photoperiod alters serum concentrations of LH, FSH and prolactin in cattle.

Animals↗
PubMed1987

Response of prepubertal ewes primed with monensin or progesterone to administration of FSH.

Prepubertal ewe lambs were treated with FSH after progesterone priming for 12 days (Group P), monensin supplementation for 14 days (Group M) or a standard diet (Group C). Serial blood samples were taken for LH and progesterone assay, and ovariectomy was performed on half of each group 38-52 h after start of treatment to assess ovarian function, follicular steroid production in vitro and the concentration of gonadotrophin binding sites in follicles. The remaining ewe lambs were ovariectomized 8 days after FSH treatment to determine whether functional corpora lutea were present. FSH treatment was followed by a preovulatory LH surge which occurred significantly later (P less than 0.05) and was better synchronized in ewes in Groups P and M than in those in Group C. At 13-15 h after the LH surge significantly more large follicles were present on ovaries from Group P and M ewes than in Group C. Follicles greater than 5 mm diameter from ewes in Groups P and M produced significantly less oestrogen and testosterone and more dihydrotestosterone, and had significantly more hCG binding sites, than did similar-sized follicles from Group C animals. Ovariectomy on Day 8 after the completion of FSH treatment showed that ewes in Groups P and M had significantly greater numbers of functional corpora lutea. These results indicate that, in prepubertal ewes, progesterone priming and monensin supplementation may delay the preovulatory LH surge, allowing follicles developing after FSH treatment more time to mature before ovulation. This may result in better luteinization of ruptured follicles in these ewes, with the formation of functional corpora lutea.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Monitoring ovarian function and pregnancy in the giant panda (Ailuropoda melanoleuca) by evaluating urinary bioactive FSH and steroid metabolites.

Urinary excretion of oestrone conjugates, pregnanediol-3 alpha-glucuronide (PdG) and 20 alpha-hydroxypregn-4-en-3-one were measured from 8 weeks before oestrus to 2 weeks post partum and bioactive FSH was monitored during the periovulatory interval in a female giant panda. A biphasic urinary bioactive FSH excretory profile appeared to indicate a broad (approximately 10 day) follicular phase followed by a sharp preovulatory bioactive FSH surge coincident with an acute increase in urinary oestrone conjugates and behavioural oestrus. Weekly concentrations of urinary oestrone conjugates and PdG increased (P less than 0.001) by Week 9 of gestation with 20 alpha-hydroxypregn-4-en-3-one levels increasing 10-30-fold (P less than 0.001) between Weeks 11 and 14. These observations indicate that the monoestrous giant panda does not appear to require a prolonged period of endogenous FSH release or multiple FSH peaks for ovarian priming and follicle selection to proceed normally. Furthermore, the delayed rise in urinary steroid excretion during the second half of gestation in the giant panda supports the concept of delayed implantation while the estimation of steroid conjugates in urine offers a non-invasive approach for monitoring pregnancy status in this endangered species.

20-alpha-Dihydroprogesterone↗