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PubMed2002

FSH- and LH-cells originate as separate cell populations and at different embryonic stages in the chicken embryo.

The histological distribution of gonadotrophs containing either LH or FSH, but not both gonadotropins, has been demonstrated before in the juvenile and adult chicken throughout the caudal and cephalic anterior pituitary lobes. In the present investigation, the distribution of FSH- and/or LH-containing gonadotrophs was further investigated in the chicken embryo by use of the same homologous antibodies as used in our earlier study. Fluorescent dual-labeling immunohistochemistry revealed that during embryogenesis LH and FSH reside exclusively in separate gonadotrophs, as has been described before in the post hatch bird. LH-immunoreactive cells were observed for the first time at day 9 of embryogenesis. This is as much as 4 days earlier than the FSH-immunoreactive cells, which appeared at day 13 of embryogenesis. Our results confirm that FSH- and LH-containing gonadotrophs are distributed throughout both lobes of the anterior pituitary. No conspicuous differences were observed between the sexes in any of the aspects investigated. The described situation is unique in that it seems to imply the existence of separate cell lineages for FSH- and LH-producing cells, as opposed to the single gonadotrope lineage described in all other species studied so far, with the exception of bovine. Our data indeed raise the question as to which signaling and/or transcription factors may cause the unique dichotomy observed in the chicken gonadotrophs.

Animals↗
PubMed2001

Dexamethasone increases inhibin and estradiol secretion mediated by endogenous FSH in equine chorionic gonadotropin (eCG)-primed immature female rats.

In the present study, we have examined whether the effects of dexamethasone on follicle stimulating hormone (FSH) secretion were mediated by hypophysiotropic factors, and whether the increased levels of FSH induced by dexamethasone can stimulate ovarian functions in equine chorionic gonadotropin (eCG)-primed immature female rats. Dexamethasone (500 microg) significantly increased serum concentrations of FSH in hypophysectomized rats implanted with pituitary under the kidney capsule, as well as in intact rats. Serum concentrations of inhibin and estradiol in eCG (2.5, 5 i.u.)-primed rats were significantly increased by simultaneous treatment with dexamethasone (500 microg) and eCG. These simultaneous effects were not confirmed in hypophysectomized rats. The results had shown that hypophysiotropic factors do not mediate the selective increase of FSH secretion caused by dexamethasone. Dexamethasone induces the excess amount of FSH secretion from anterior pituitary and this FSH can stimulate inhibin and estradiol secretion in eCG-primed immature female rat.

Animals↗
PubMed1999

Progesterone and regulation of the follicle-stimulating hormone (FSH-beta) gene.

Progesterone (P) biphasically modulates follicle-stimulating hormone (FSH) secretion in the rat both in vivo and in vitro with the duration of estrogen priming determining the biphasic nature of the P action, probably through estrogen up-regulation of the anterior pituitary progesterone receptor (PR) levels. P has been also shown to regulate anterior pituitary levels of FSH-beta mRNA in the rat. Although the mechanism of this action has not been determined, steroids may regulate gene expression through the binding of liganded receptors to gene sequences known as hormone response elements (HRE); however, it is not known whether HRE's exist on the rat FSH-beta gene. We have localized a series of progesterone response elements (PRE)-like sequences on the rat FSH-beta gene and have begun testing the hypothesis that P modulates the expression of the rat FSH-beta gene through the direct binding of the P/PR complex to these PRE-like sequences. Electromobility shift assays indicate that these PRE-like sequences bind PR with high affinity and specificity. In addition, when a 361-base pair sequence, which contains the three PRE-like sequences localized in the upstream region of the gene, was cloned into a luciferase expression vector driven by a heterologous promoter and transiently transfected into anterior pituitary cell cultures, progestin stimulation elicited increased luciferase expression. These results indicated that the 361-base pair sequence conferred P-responsiveness to a heterologous promoter. The data further suggest that FSH synthesis in the rat is modulated by direct binding of PR to PRE-like sequences.

Animals↗
PubMed2001

Short-term treatment with a controlled internal drug releasing (CIDR) device and FSH to induce fertile estrus and increase prolificacy in anestrous ewes.

The objectives were to evaluate, in anestrous ewes, the effectiveness of a CIDR-G device (0.3 g progesterone) administered for 5 d to induce estrus; and FSH (Folltropin; 55 mg NIH-FSH-P1 equivalent) in saline:propylene glycol (1:4) 24 h before insert removal (Day 0), to increase ovulation rate and prolificacy. Ewes of mixed breeding were assigned at random to 3 treatments: control (C; n = 125), 5 d progesterone (P5; n = 257) and 5 d progesterone plus FSH (P5F; n = 271). Intact rams were joined at insert removal and ewes were observed every 24 h for 3 d. On Day 14, the ovulation rates of all ewes detected in estrus in the treated groups were determined using transrectal ultrasonography. Rams were removed on Day 26 to 31. Ewes were examined for pregnancy then, and again 20 to 25 d later to detect ewes that conceived to the second service period. Percentage of ewes marked by rams was higher in progesterone-treated (77%) than in C (20%; P < 0.01), but did not differ between P5 and P5F. The ovulation rate (1.95+/-0.04) did not differ due to FSH. Conception (68%) and pregnancy (52%) rates were higher in progesterone-treated (P < 0.01) than in C (0%) ewes. Estrous response varied quadratically with time after ram introduction, and the conception rate varied quadratically with the time of observation of onset of estrus. Over two service periods more progesterone-treated than C ewes lambed (65 vs 45%; P < 0.01). Lambs born per ewe exposed (0.7+/-0.1, 1.0+/-0.1, and 1.1+/-0.1 for C, P5 and P5F, respectively) was increased by progesterone (P < 0.05). Litter size to the first service period (1.59+/-0.04) and overall (1.54+/-0.03) did not differ among treatment groups. FSH-treated ewes tended to have more lambs (1.67+/-0.1) than did ewes receiving progesterone alone (1.5+/-0.1; P = 0.06) and than did ewes lambing to the second service period (1.5+/-0.1; P = 0.06). In summary, a 5-d progesterone pre-treatment of anestrous ewes induced estrous cycles and increased the pregnancy rates. A single injection of FSH only tended to increase litter size.

Animals↗
PubMed2002

Comparisons of estradiol, LH and FSH patterns in pregnant and nonpregnant beagle bitches.

To characterize plasma estradiol, LH and FSH patterns of secretion during the bitch estrous cycle, blood samples were obtained daily from 15 days before until 135 days after the LH surge in 10 pregnant and 10 nonpregnant beagle bitches. After an initial increase between days 15 and 10 and an expected proestrous peak, estradiol concentrations increased again from days 9-12 (corresponding to cytological metestrus) from basal values observed around day 9 after the LH surge, and remained significantly elevated throughout the luteal phase both in pregnant and nonpregnant animals. Concomitantly with the end of the luteal phase, plasma concentrations of estradiol returned to basal values in both groups. During the mid- to late-luteal phase, mean basal LH secretion was significantly elevated throughout in the pregnant relative to the nonpregnant animals. However, in nonpregnant animals, pulsatility was increased and peaks of higher amplitude were observed. The plasma FSH profiles, determined by a specific homologous RIA, differed significantly between pregnant and nonpregnant bitches during the last two-thirds of the luteal phase with a mean FSH level more elevated during pregnancy. The FSH level then decreased around parturition and low concentrations during lactation period were observed. The FSH concentrations remained steady in nonpregnant luteal phases from early luteal phase through mid-anestrus. The differences in pregnant and nonpregnant LH and FSH concentrations suggest pregnancy differences in regulation of the corpus luteum. Finally, the elevated estradiol concentrations observed during the luteal phase of both pregnant and nonpregnant animals suggest that an ovarian production of estrogens may be involved in overall corpus luteum regulation in dogs as in other species.

Animals↗
PubMed2002

Effect of follicular status on superovulatory response in ewes is influenced by presence of corpus luteum at first FSH dose.

The present study was developed to assess possible effects on ovulatory response and embryo yields arising from the presence of a corpus luteum (CL) at the time of initiation of the progestagen treatment used in superovulatory protocols in sheep. In breeding season, estrus was synchronized in 25 Manchega ewes using 40 mg FGA sponges for 14 days, together with a single dose of 125 microg of cloprostenol on Day 12, with Day 0 as day of progestagen insertion. Superovulatory treatment consisted of eight decreasing doses (1.5 x 3 ml, 1.25 x 2 ml, and 1 x 3 ml) of Ovagen twice daily from 60 h before to 24 h after sponge removal. The presence or absence of corpora lutea was assessed by transrectal ultrasonography at progestagen insertion and at first FSH dose. Number and size of all follicles > or = 2 mm were also evaluated at first FSH dose. The number of corpora lutea and the number and viability of recovered embryos in response to the treatment were evaluated 7 days after sponge removal. No significant effect on ovarian response of the presence of a CL at sponge insertion in 21 of the 25 ewes (84%) was detected. However, ewes with a CL at first FSH dose (16 ewes, 64%) yielded a higher number of transferable embryos (7.2 +/- 1.4 versus 2.7 +/- 0.7, P < 0.05), since the embryo degeneration rate was increased in sheep without a CL (42.5% versus 12.7%, P < 0.01). Analysis of possible effects derived from the presence of a large presumptively dominant follicle (> or = 6 mm) at first FSH dose showed that both recovery and viability rates were lowest (P < 0.05) in ewes bearing a large follicle in the absence of a CL (40.5 and 50.6%, respectively), and highest in ewes that did not show a large follicle but in which a CL was present (73.9 and 85.2%). The final number of transferable embryos was very different between groups (10.2 versus 1.8, P < 0.01). These results indicate that the number and quality of embryos obtained from superovulated ewes is affected by the presence of a CL prior to the first FSH dose (i.e. by the stage of the estrous cycle at progestagen insertion) and also by an interaction with suppressive effects from large dominant follicles. This finding suggests the existence of some effects on follicular population prior to the FSH treatment that may compromise follicle and oocyte developmental competence. It seems reasonable to hypothesize that superovulatory yields would be increased by beginning the treatment during the early-luteal phase of the estrous cycle, allowing for the presence of a CL along with the progestagen treatment.

Animals↗
PubMed1996

Effect of gestation on GnRH-induced LH and FSH release in buffalo (Bubalus bubalis).

This study examined the effect of gestation on the hypophyseal responsiveness of buffalo to GnRH-induced LH and FSH release. Peripheral plasma LH and FSH concentrations were measured at 1 h before and upto 6 h after administration of GnRH (1 ug/kg body weight) or saline at Days 60, 150 and 240 of gestation in 2 groups of buffalo (n = 4 each). Basal LH concentrations did not vary at the 3 stages of gestation, while basal FSH concentrations exhibited a significant reduction (P < 0.05) from Day 60 to Day 150 of gestation. There was a significant reduction in the total LH (P < 0.05) and FSH (P < 0.01) released in response to GnRH from Day 60 to Day 240 of gestation. The duration of LH and FSH peaks and the time to attain peak concentration was not affected by the stage of gestation. The results of the present study point to a progressive decline in LH and FSH release responses to GnRH during the advancement of gestation in the buffalo.

Journal Article↗
PubMed1997

Baculovirus-insect cell production of bioactive porcine FSH.

The in vitro and in vivo bioactivity of recombinant porcine FSH (rpFSH) produced from insect cells through use of a baculovirus expression system were studied and compared with those of natural FSH preparations. Determination of in vitro bioactivity, using the rat Sertoli cell aromatase bioassay, indicated that rpFSH is as active as purified pituitary FSH. Determination of in vivo bioactivity, using the mouse uterine weight bioassay, indicated that rpFSH is as active as purified pituitary FSH. Using the mouse Leydig cell testosterone bioassay, it was demonstrated that the intrinsic LH bioactivity of rpFSH is negligible. The increases in ovarian and uterine weight, and the stimulation in follicular growth in immature hypophysectomized rats induced by rpFSH supplemented with hCG were comparable to those induced by natural FSH preparations. Furthermore, rpFSH alone in hypophysectomized mice stimulated preantral follicular growth to preovulatory stages, and the subsequent injection of hCG caused ovulation. These results demonstrate that in vitro and in vivo biological characteristics of rpFSH produced from baculovirus-insect cells are indistinguishable from those of FSH isolated from natural sources.

Journal Article↗
PubMed1997

The dominant follicle exerts an interovarian inhibition on FSH-induced follicular development.

An experiment was conducted to evaluate the role of the dominant follicle (DF) of the first wave in regulating follicular and ovulatory responses and embryonic yield to a superovulation regime with FSH-P. Twenty normally cycling Holstein-Freisian heifers (n = 20) were synchronized with GnRH and pgf(2alpha) and randomly assigned to a control or a treated group (n = 10 each). Treated heifers had the first wave dominant follicle removed via transvaginal, ultrasound-guided aspiration on Day 6 after a synchronized estrus. All heifers received a total of 32 mg FSH-P given in decreasing doses at 12 h intervals from Day 8 to Day 11 plus two injections of pgf(2alpha) (35 mg and 20 mg, respectively) on Day 10. Heifers were inseminated at 6 h and 16 h after onset of estrus. Follicular dynamics were examined daily by transrectal ultrasonography from Day 4 to estrus, once following ovulation, and at the time of embryo collection on Day 7. Blood samples were collected daily during the superovulatory treatment and at embryo collection. Follicles were classified as: small, </= 5 mm; medium, 6-9 mm; or large, >/= 10 mm. Aspiration of the dominant follicle was associated with an immediate decrease in large follicles, and a linear rate increase in small follicles from Day 4 to Day 8 just prior to the FSH-P injections, (treatment > control: +0.33 vs. -0.22, number of small follicles per day; P < 0.10). During FSH-P injections, the increase in number of medium follicles was greater (P < 0.01) for treatment on Day 9-11 (treatment > control: Day 9, 3.2 > 1.8; Day 10, 9.2 > 4.7; Day 11, 13.1 > 8.3; +/- 0.56). Number of large follicles was greater in treatment at Day 11 (5.12 > 1.4 +/-0.21; P < 0.01). Mean number of induced ovulatory follicles (difference between number of follicles at estrus and Day 2 after estrus) was greater in treatment (13.4 > 6.3 +/- 1.82; P < 0.01). Plasma estradiol at Day 11 during FSH-P treatment was greater in treatment (32.5 > 15.8 +/- 2.6; P < 0.01). Plasma progesterone at embryo flushing (Day 7 after ovulation) was greater in treatment (7.4 > 4.9; P < 0.02); technical difficulties at embryo recovery reduced sensitivity of embryonic measurements. No changes in the distribution of unfertilized oocytes and embryo developmental stages were detected between control and treatment groups. Presence of dominant follicle of the first wave inhibited intraovarian follicular responses to exogenous FSH.

Journal Article↗
PubMed1998

Circadian and pulsatile variations in plasma levels of inhibin, FSH, LH and testosterone in adult Murrah buffalo bulls.

The present study investigated pulsatile and circadian variations in the circulatory levels of inhibin, gonadotrophins and testosterone. Six adult buffalo bulls (6 to 7 yr of age) were fitted with indwelling jugular vein catheters, and blood samples were collected at 2-h intervals for a period of 24 h and then at 15-min interval for 5 h. Plasma concentrations of inhibin, FSH, LH and testosterone were determined by specific radioimmunoassays. Plasma inhibin levels in Murrah buffalo bulls ranged between 0.201 to 0.429 ng/mL, with a mean of 0.278 +/- 0.023 ng/mL. No inhibin pulses could be detected during the 15-min sampling interval. Plasma FSH levels ranged between 0.95 to 3.61 ng/mL, the mean concentration of FSH over 24 h was 1.66 +/- 0.25 ng/mL. A single FSH pulse was detected in 2 of 6 bulls. The LH levels in peripheral circulation ranged between 0.92 to 9.91 ng/mL, with a mean concentration of 3.33 +/- 1.02 ng/mL. Pulsatility was detected in LH secretion with an average of 0.6 pulses/h. Plasma testosterone levels in 4 buffalo bulls ranged from 0.19 to 2.99 ng/mL, the mean level over 24 h were 1.34 +/- 0.52 ng/mL. Testosterone levels in peripheral circulation followed the LH secretory pattern, with an average of 0.32 pulses/h. The results indicate parallelism in inhibin, FSH and LH, and testosterone secretory pattern. Divergence in LH and FSH secretory patterns in adult buffalo bulls might be due to the presence of appreciable amounts of peripheral inhibin.

Animals↗
PubMed2000

Differential regulation by FSH and IGF-I of extracellular matrix IGFBP-5 in bovine granulosa cells: effect of association with the oocyte.

Inhibition of insulin-like growth factor (IGF)-I induced DNA synthesis in bovine oocyte-cumulus complexes (OCCs) caused by follicle-stimulating hormone (FSH) has been linked to changes in the extracellular matrix which do not occur in mural granulosa cells (MGCs). We investigated regulation by IGF-I and FSH of secreted and extracellular matrix entrapped IGF-binding proteins. OCCs and MGCs from bovine ovaries were cultured in media supplemented with IGF-I and FSH for 24 h. Culture media and extracellular matrix were analysed for IGF-binding proteins by Western ligand blot and immunoblot and found to contain principally IGFBP-3 and -5. The combined treatment of IGF-I and FSH increased the concentration of IGFBP-3 in OCC and MGC conditioned media by 4- and 6-fold, respectively. Treatment of OCCs and not MGCs with IGF-I and FSH together increased extracellular matrix IGFBP-5 by 2.5-fold. The differential regulation of extracellular matrix IGFBP-5 in OCCs compared to MGCs suggest involvement of changes in the extracellular matrix brought about by IGF-I and FSH in overall regulation of IGF-I in the ovarian follicle.

Animals↗
PubMed2001

Operation of the follicle-stimulating hormone (FSH)-inhibin B feedback loop in the control of primate spermatogenesis.

This paper reviews our current understanding of the function and operation of the follicle-stimulating hormone (FSH)-inhibin feedback loop in the male rhesus monkey (Macaca mulatta). Inhibin B is the major testicular inhibin in the monkey, and the pattern of secretion of this hormone during postnatal development is temporally coupled to that of gonadotropin. Inhibin B secretion by the Sertoli cell is stimulated by FSH and inhibited by luteinizing hormone (LH), the latter presumably acting via Leydig cell production of testosterone (T). The dynamics of the FSH-inhibin B feedback loop in the adult monkey is revealed following unilateral orchidectomy (UO). Interestingly, a sustained, 50% deficit in inhibin B secretion occurs after UO and this persistent error signal, in turn, results in elevated concentrations of FSH in the circulation. The elevated secretion of FSH appears to be the principal drive for the increased sperm output by the remaining testis. Available data for the functioning of the FSH-inhibin B feedback loop in the human male are placed in perspective, and a model for the negative feedback regulation of sperm number in primates is proposed.

Animals↗
PubMed1991

An ACTH and FSH producing invasive pituitary adenoma with Crooke's hyalinization.

We report on a patient with ACTH and FSH producing invasive pituitary adenoma complaining of cutaneous pigmentation. Elevations in plasma ACTH, beta-endorphin and cortisol levels as well as urinary 17-OHCS and cortisol excretion were found. Serum FSH concentration was just within the upper limit of the normal range, whereas serum LH level was reduced and alpha-subunit level was normal. Roentogenographic examination showed an almost complete loss of sellar floor and destruction of the posterior clinoids and dorsum sella. CT scan and MRI demonstrated an enlarged tumor invasion of the clivus and its extension to the sphenoid sinus. After subtotal removal of the large pituitary tumor, serum cortisol and plasma beta-endorphin levels as well as plasma ACTH concentrations returned to normal and serum FSH levels also remarkably decreased. Histologically, the tumor corresponded to a chromophobe, slightly PAS positive adenoma. These tumor cells exhibited positive immunostaining with antibody to ACTH (1-24), beta-LPH, beta-endorphin and FSH, while immunostaining of the adenoma cells was negative for LH, TSH, GH and prolactin. The immunogold technique also demonstrated ACTH and FSH particles in the secretory granules in the cytoplasm of the adenoma cells. Some of the tumor cells disclosed Crooke's hyalinization and type I microfilament occupied most of the cytoplasm. In the present study, a very rare case of ACTH and FSH producing invasive pituitary adenoma is reported.

Adenoma↗
PubMed2003

The effect of dietary protein restriction on the secretion of LH and FSH in pre-pubertal female lambs.

The effect of restricted dietary protein on the synthesis, storage and release of LH and FSH was studied in pre-pubertal female lambs. The experiment started when the lambs were aged 12 weeks and weighed 26.0+/-1.6 kg. It was conducted for 25 weeks. The lambs were fed isocaloric diets containing either a restricted level of crude protein (8% CP; n=6; treatment R) or an elevated one (18% CP; n=4; treatment E). At 37 weeks of age and before the first oestrous cycle, blood samples were collected over 6 h at 10 min intervals for LH assay. The lambs were slaughtered and their brains recovered and fixed in situ. Immuno-reactive (IR) LH and FSH cells were localised by immunohistochemistry techniques. Messenger RNA analyses used by non-isotope in situ hybridisation with sense and anti-sense riboprobes from beta subunits of LH and FSH cDNA clones. Data were generated using computer analysis to measure the proportion of IR and/or hybridising cells and their optical density for immuno-staining and hybridisation signal. Plasma LH was measured by RIA. The daily live-weight gains were 56.5+/-13.1 g and 97.8+/-14.3 g for R and E lambs, respectively (P<0.05), so that final weights at slaughter were 36.1+/-1.97 kg and 39.1+/-3.44 kg, respectively (P<0.05). The number of cells expressing LH beta mRNA and the optical density of this hybridisation signal was significantly (P<0.001) lower in the R lambs but the number of IR LH positive cells was higher (P<0.001) than for the E lambs. The concentration of LH in the plasma of R sheep was lower (P<0.05) than the E group and this response was associated with a decrease (P<0.05) in LH pulse frequency and amplitude. Dietary protein concentration appeared to have no effect on the IR in FSH cells or on the expression of FSH beta mRNA. In summary, the low protein diet influenced the body weight and weight gain of growing lambs and exerted an inhibitory effect on the synthesis and the release of LH in the pituitary gonadotrophs. No such effect was observed for FSH. It was concluded that the protein concentration of the diet consumed during the growth of female lambs may be an important modulator of processes leading to the pre-pubertal rise in LH.

Animals↗
PubMed1997

Superovulation in cattle: effect of FSH type and method of administration on follicular growth, ovulatory response and endocrine patterns.

Although different FSH preparations and injection regimens are used to superovulate cattle, the optimum treatment regimen and blood concentrations of FSH to induce effective superovulatory responses are currently not known. The current objective was to evaluate the pattern of follicular growth, oestradiol-17 beta(E2) concentrations and yield of embryos in heifers following superovulation with two different pFSH preparations reportedly differing in LH content. In experiment 1, 90 synchronised heifers were superovulated at mid-cycle using a 2 x 2 factorial design comparing Folltropin (Vetrepharm; low LH) with Pluset (Serovet; FSH:LH ratio 1:1) administered either as a single or multiple (8 for Folltropin, MF and 10 for Pluset, MP) injections. Animals were inseminated during oestrus which was induced with prostaglandin F2 alpha analogue and embryos were recovered 7 days later. Overall, Pluset treatments compared with Folltropin resulted in more ovulations and unfertilized or degenerate embryos (P < 0.05). Multiple injections resulted in more (P < 0.05) freezable (MF = 55 +/- 1.2; MP = 3.8 +/- 1.0) and transferable embryos (MF = 2.68 +/- 0.9; MP = 2.71 +/- 0.9) than single injections (SF = 2.2 +/- 0.5 and 1.0 +/- 0.3 respectively; SP = 2.6 +/- 0.8 and 1.3 +/- 0.4 respectively); there was also a higher (P < 0.05) percentage embryo recovery rate. In two subsequent experiments, animals (n = 17) were superovulated with either single or multiple injections of Folltropin or Pluset as described and blood samples were collected and analysed for E2 concentrations. Ovarian scanning was carried out until 72 h after the first FSH injection, to count medium (5-9 mm) and large (> or = 10 mm) follicles. Heifers treated with SP had higher E2 concentrations in comparison with heifers treated with SF at 18, 36-48 and 84-96 h after the FSH injection. There were no differences in E2 concentrations in heifers treated with MF or MP treatments. Heifers treated with SP had greater numbers of follicles compared to SF treated heifers (21.0 +/- 3.1 vs 13.9 +/- 2.2; P = 0.089) on the third day after FSH injection. There were no differences between the numbers of medium and large follicles in heifers treated with MF or MP at any time throughout the experimental period. These data indicate that a single injection of Folltropin or Pluset can result in multiple ovulations and that the E2 profiles are different following single injections of either Folltropin or Pluset.

Animals↗
PubMed2000

Effects of exogenous FSH on follicular recruitment in a viviparous lizard Niveoscincus metallicus (Scincidae).

In the viviparous skink Niveoscincus metallicus clutch size appears to be determined before vitellogenesis, and is not altered later by follicular atresia or embryonic loss. This suggests that the number of follicles recruited is determined by the endocrine environment early in the vitellogenic period. Through a series of experiments in which we manipulated gonadotropin concentrations by administering exogenous FSH, we aimed to investigate this hypothesis. Pre-vitellogenic females showed no response to exogenous ovine FSH. In early vitellogenic females, FSH induced follicular recruitment: follicles were enlarged and clutch size increased by recruitment of a second cohort of follicles; some females also ovulated. Females treated with FSH in mid-vitellogenesis had elevated mean plasma estradiol concentrations compared to controls; no follicular recruitment was observed, but most of these animals ovulated. Females treated with a range of doses of FSH in late vitellogenesis ovulated at least one month before natural ovulation, again without recruitment of extra follicles. It appears therefore that in Niveoscincus metallicus exogenous FSH can induce recruitment of additional follicles only if administered during early vitellogenesis. We conclude that in this species clutch size is determined by proximate environmental factors influencing gonadotropin levels early in follicular recruitment, and cannot be increased even if conditions become more favourable once vitellogenesis is established.

Animals↗
PubMed2004

Evaluation of relative role of LH and FSH in restoration of spermatogenesis using ethanedimethylsulphonate-treated adult rats.

Spermatogenesis is a complex process, and previous studies have clearly established the role for testosterone in its maintenance. However, the role of FSH remains controversial, although several lines of evidence suggest its importance in initiation of spermatogenesis. In the present study, the relative roles of FSH and LH have been evaluated using specific antisera capable of neutralizing endogenous hormones in adult male rats following ethanedimethylsulphonate (EDS) treatment. Restoration of spermatogenesis in EDS-treated rats was monitored following FSH or LH deprivation by histological analysis and flow cytometry. Deprivation of FSH resulted in a reduction of seminiferous tubule diameter and spermatogonial number, which was much more drastic than that observed following LH deprivation. More importantly, FSH deprivation was associated with a significant reduction in the number of pachytene spermatocytes. These results provide evidence for a definite role for FSH in regulation of spermatogenesis, in addition to confirming the role of LH in spermatogenesis via testosterone.

Animals↗
PubMed1999

The relation of optical density of seminal plasma with serum FSH and LH levels in azoospermic patients.

The aim was to investigate the relation between optical density of seminal plasma, serum follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels in azoospermic patients and to establish criteria depending on optical density measurements in order to estimate serum FSH and LH levels. Optical density of seminal plasma and serum FSH and LH levels were measured in 45 azoospermic patients. The semen samples with an optical density (OD) of more than 0.5 showed normal levels of FSH and LH, while those with less than 0.5 were observed to have high levels of FSH and LH. The optical density of seminal plasma can be used in the prediction of serum FSH and LH levels in azoospermic patients.

Follicle Stimulating Hormone↗