scholarly journals Effects of ovarian follicle ablation on FSH, oestradiol and inhibin A concentrations and growth of other follicles in sheep

Reproduction ◽  
2002 ◽  
pp. 59-66 ◽  
Author(s):  
AC Evans ◽  
JD Flynn ◽  
P Duffy ◽  
PG Knight ◽  
MP Boland
Keyword(s):  
Ovarian Follicle ◽  
Oestrous Cycle ◽  
Maximum Diameter ◽  
Control Group ◽  
Follicular Growth ◽  
Treatment Control ◽  
Inhibin A ◽  
Follicular Wave ◽  
Gonadotrophin Secretion

The aim of this study was to examine the effect of removal of the largest follicle or all visible follicles during the first follicle wave on subsequent follicular growth, steroid, inhibin A and gonadotrophin secretion in sheep. On day 4.5 of a synchronized oestrous cycle, ewes (n = 18) were assigned to one of three groups which underwent either no treatment (control), ablation of the largest follicle (largest follicle aspirated and cauterized via laparotomy) or ablation of all follicles (all visible follicles ablated). Between day 0 and day 10 of the oestrous cycle, blood samples were collected every 8 h and ovaries were examined daily using transrectal ultrasonography. The lifespan of the second largest follicle (number of days > 3 mm in diameter) was longer (6.7 +/- 0.9 days; P < 0.05) and the maximum diameter tended to be greater (4.8 +/- 0.3 mm; P = 0.07) in ewes in which the largest follicle was ablated than in the control ewes (3.8 +/- 0.4 days; 4.2 +/- 0.3 mm). There was no difference in the day of emergence of the second follicular wave between groups (day 6.9 +/- 0.4). However, the peak of the transient increase in FSH concentrations after ablation was earlier (day 5.67 +/- 0.15; P < 0.05) in ewes in which all follicles were ablated than in control ewes (day 6.72 +/- 0.36); the timing in ewes that had only the largest follicle ablated was intermediate (day 6.11 +/- 0.28). Serum inhibin A concentrations were about three-fold lower (P < 0.05) in both follicle ablation groups than in the control group. The numbers of follicles 2-3 mm in diameter during the first 3 days of the second follicular wave were greater in 'ablated ewes' (both groups had 2.6 +/- 0.2 follicles day-1) than in control ewes (1.7 +/- 0.3 follicles day-1). It is concluded that: (i) transient increases in FSH concentrations precede the emergence of follicle waves; (ii) ablation of all follicles on day 4.5 after oestrus advanced the timing of the next peak in FSH concentrations and the numbers of small follicles associated with the development of the second follicular wave; and (iii) ablation of the largest follicle resulted in an increase in the lifespan of the second largest follicle, indicating a regulatory role of large dominant follicles over smaller subordinate follicles.

Protective effects of histamine on Gq-mediated relaxation in regenerated endothelium

2014 ◽  
Vol 306 (2) ◽  
pp. H286-H290 ◽  
Author(s):  
Calvin K. Chan ◽  
Song Yan Liao ◽  
Yue Lin Zhang ◽  
Aimin Xu ◽  
Hung Fat Tse ◽  
...  
Keyword(s):  
Area Under The Curve ◽  
Treated Group ◽  
Control Group ◽  
Protective Effects ◽  
Treatment Control ◽  
Porcine Coronary Artery ◽  
Endogenous Histamine ◽  
Coronary Endothelium ◽  
Treatment Control Group

In the porcine coronary artery, regenerated endothelium is dysfunctional as regards the responses to endothelium-dependent agonists. The current study aimed to determine the possible involvement of histamine in such dysfunction. Pigs were treated chronically with pyrilamine (H1 receptor inhibitor, 2 mg·kg−1·day−1) with part of their coronary endothelium and allowed to regenerate for 28 days after balloon denudation. The results showed a reduction in relaxation to bradykinin (Gq protein dependent) only in the pyrilamine-treated group (area under the curve, 269.7 ± 13.4 vs. 142.0 ± 31.0, native endothelium vs. regenerated endothelium) but not in the control group (253.0 ± 22.1 vs. 231.9 ± 29.5, native endothelium vs. regenerated endothelium). The differences in the relaxation to serotonin (Gi protein dependent) between native and regenerated endothelium were not affected by the pyrilamine treatment (control group, 106.3 ± 17.0 vs. 55.61 ± 12.7; and pyrilamine group, 106.0 ± 8.20 vs. 49.30 ± 6.31, native endothelium vs. regenerated endothelium). These findings indicate that during regeneration of the endothelium, the activation of H1 receptors by endogenous histamine may be required to maintain the endothelium-dependent Gq protein-mediated relaxation to bradykinin, suggesting a beneficial role of the monoamine in the process of endothelial regeneration.

Progesterone as the driving regulatory force behind serum FSH concentrations and antral follicular development in cycling ewes

2011 ◽  
Vol 23 (2) ◽  
pp. 303 ◽  
Author(s):  
Tanya E. Baby ◽  
Pawel M. Bartlewski
Keyword(s):  
Luteal Phase ◽  
Follicular Development ◽  
Treated Group ◽  
Time Frame ◽  
Oestrous Cycle ◽  
Control Group ◽  
Corpora Lutea ◽  
Follicular Waves ◽  
Follicular Wave ◽  
And Control

Ovarian antral follicles in sheep grow in an orderly succession, producing typically three to four follicular waves per 17-day oestrous cycle. Each wave is preceded by a transient increase in circulating FSH concentrations. The mechanism controlling the number of recurrent FSH peaks and emerging follicular waves remains unknown. During the ewe’s oestrous cycle, the time between the first two FSH peaks and days of wave emergence is longer than the intervals separating the ensuing FSH peaks and follicular waves. The prolonged interpeak and interwave interval occurs early in the luteal phase when low levels of progesterone are secreted by developing, or not fully functional, corpora lutea (CL). The purpose of the present study was to determine the effect of varying progesterone (P4) levels on circulating concentrations of FSH and antral follicular development in sheep. Exogenous P4 (15 mg per ewe, i.m.) was administered twice daily to six cycling Rideau Arcott × Dorset ewes from Day 0 (ovulation) to Day 4 (the mean duration of the interwave interval); six animals served as controls. Follicular growth was monitored in all animals by daily transrectal ultrasonography (Days 0–9). Jugular blood samples were drawn twice a day from Day 0 to Day 4 and then daily until Day 9 to measure systemic concentrations of P4, FSH and 17β-oestradiol (E2). The first FSH peak after ovulation was detected on Days 1.5 ± 0.2 and 4.2 ± 0.2 in treated and control ewes, respectively (P < 0.05). The next FSH peak(s) occurred on Day 3.9 ± 0.3 in the treated group and on Day 6.4 ± 0.5 in the control group. Consequently, the treated group had, on average, three follicular waves emerging on Days 0, 3 and 6, whereas the control group had two waves emerging on Days 0 and 5. Mean serum E2 concentrations were greater (P < 0.05) in control compared with treated ewes on Days 1.3, 2.3, 3.3, 4.0 and 4.3 after ovulation. In summary, creation of mid-luteal phase levels of P4 in metoestrus shortened the time to the first post-ovulatory FSH peak in ewes, resulting in the emergence of one more follicular wave compared with control ewes during the same time frame. Therefore, P4 appears to be a key endocrine signal governing the control of periodic increases in serum FSH concentrations and the number of follicular waves in cycling sheep.

Surgical denervation of porcine ovaries during the middle luteal phase of the oestrous cycle changes their morphology and steroidogenic activity

2007 ◽  
Vol 55 (1) ◽  
pp. 107-122 ◽  
Author(s):  
Barbara Jana ◽  
Anna Dzienis ◽  
Joanna Wojtkiewicz ◽  
Monika Kaczmarek ◽  
M. Majewski
Keyword(s):  
Luteal Phase ◽  
Oestrous Cycle ◽  
Side Chain ◽  
Control Group ◽  
Nerve Terminals ◽  
Dramatic Reduction ◽  
Chain Cleavage ◽  
Neuropeptide Tyrosine ◽  
Ovarian Nerves

Changes in both the morphology and the steroidogenic activity of porcine ovaries denervated surgically on day 12 of the oestrous cycle were studied. Neurectomy of the plexus and the superior ovarian nerves caused a dramatic reduction in the number (or even a disappearance) of dopamine-β-hydroxylase- and/or neuropeptide tyrosine-immunoreactive nerve terminals. On day 20 of the subsequent oestrous cycle, the number of small follicles increased (P < 0.01) and that of large follicles decreased (P < 0.05) in the denervated ovaries, as compared to the controls. Neurectomy led to a decrease in the level of progesterone (P 4 ; P < 0.001) and androstenedione (A 4 ; P < 0.01) in the fluid from small follicles, A 4 (P < 0.001) and testosterone (T; P < 0.05) in the fluid from medium-sized follicles, as well as in the content of all these steroids in the fluid from large-sized follicles (P < 0.001 for P 4 and P < 0.05 for A 4 and T). Denervation also caused a decrease in the content of A 4 (P < 0.01) and T (P < 0.001) in the wall of follicles. Neurectomy resulted in a significant increase in the immunoexpression of cholesterol side-chain cleavage cytochrome P450 in the follicles and a decrease of 3β-hydroxysteroid dehydrogenase. After denervation, plasma levels of LH, P 4 , A 4 , T, oestrone and oestradiol-17β were lower (P < 0.05–0.001) on the particular days of the study than in the control group. Our data revealed that the denervation of ovaries during the middle luteal phase of the oestrous cycle in gilts caused distinct changes in both the morphology and the steroidogenic activity of the organ, confirming an important role of the peripheral nervous system in the control of the gonad in this species.

Role of the subcommissural organ in the control of gonadotrophin secretion in the female rat

1982 ◽  
Vol 95 (2) ◽  
pp. 207-213 ◽  
Author(s):  
Patrizia Limonta ◽  
Roberto Maggi ◽  
Luciano Martini ◽  
Flavio Piva
Keyword(s):  
Subcommissural Organ ◽  
Oestrous Cycle ◽  
Female Rats ◽  
Ovariectomized Rats ◽  
Normal Female ◽  
Female Rat ◽  
Thermal Lesions ◽  
Gonadotrophin Secretion

Thermal lesions were placed in the subcommissural organ (SCO) of female rats with normal cycles and long-term ovariectomized rats. In normal female rats SCO lesions disrupted the oestrous cycle in more than half of the animals, the majority of which entered a state of prolonged dioestrus. In these animals, serum gonadotrophin levels were similar to those of rats with regular cycles on day 2 of dioestrus. In animals in which the oestrous cycle was maintained, a delayed LH surge occurred on the day of pro-oestrus and the pro-oestrous FSH surge was absent. The usual increase in FSH on the day of oestrus was present. Lesions in the SCO did not change the high gonadotrophin levels typical of ovariectomized animals. These results suggested that the SCO may play a role in the control of the cyclic but not the tonic release of the gonadotrophins. In particular, it appears that the SCO might be involved in the regulation of the hypersecretion of FSH during the day of pro-oestrus.

Personal Best (PB) Goal Setting and Students’ Motivation in Science: A Study of Science Valuing and Aspirations

2014 ◽  
Vol 31 (2) ◽  
pp. 85-96 ◽  
Author(s):  
Andrew J. Martin ◽  
Tracy L. Durksen ◽  
Derek Williamson ◽  
Julia Kiss ◽  
Paul Ginns
Keyword(s):  
Secondary School ◽  
Goal Setting ◽  
Learning Goals ◽  
Control Group ◽  
Treatment Control ◽  
School Students ◽  
Correlational Research ◽  
Treatment Control Group ◽  
Primary And Secondary School

To build on prior correlational research into personal best (PB) goals and motivational outcomes, an experimental study was conducted to assess the role of PB goal setting in gains (or declines) in students’ motivation in science (viz. biology, anatomy, health). The study (comprising N = 71 elementary/primary and secondary school students) applied a pre/post-treatment/control group experimental design to test whether setting a PB learning goal in a self-paced science education program (conducted in a museum context) leads to growth in science valuing and science aspirations. The treatment group (PB goal setting), but not the control group, demonstrated significant growth in science aspirations (but not valuing) between pre- and post-testing. This study provides support for the proposition that PB learning goals are associated with motivational growth in students’ lives. Findings also hold implications for museum-based education programs for students.

scholarly journals 15EFFECT OF DOSE OF ESTRADIOL VALERATE ON OVARIAN FOLLICULAR DYNAMICS IN CIDR-TREATED BEEF COWS

2004 ◽  
Vol 16 (2) ◽  
pp. 130 ◽  
Author(s):  
R.J. Mapletoft ◽  
M.G. Colazo ◽  
J.A. Small ◽  
D.R. Ward ◽  
J.P. Kastelic
Keyword(s):  
Ovarian Follicle ◽  
Animal Health ◽  
Beef Cows ◽  
Estradiol Valerate ◽  
Control Group ◽  
Dominant Follicle ◽  
Follicular Wave ◽  
Follicle Diameter ◽  
Growth Profiles ◽  
Follicular Dynamics

The objective was to investigate the effect of dose of estradiol valerate (EV) on ovarian follicular growth profiles, intervals to follicular wave emergence and, following CIDR removal, estrus and ovulation in beef cows. On Day 0, 43 non-lactating, crossbred beef cows, 3 to 9 yr of age and at random stages of the estrous cycle, received a CIDR (Bioniche Animal Health; Belleville, Ontario, Canada) and were randomly allocated to one of four groups to receive no further treatment (Control; n=10), or an injection of 1mg (n=11), 2mg (n=10), or 5mg (n=12) i.m. of EV (Sigma Chemical Co, St. Louis, MO, USA) in 2mL canola oil. On Day 7, CIDR were removed and cows received 500μg i.m. of cloprostenol (Estrumate, Schering Plough Animal Health, Pointe-Claire, Quebec, Canada). Ovaries were examined by transrectal ultrasonography once daily until 48h after CIDR removal to detect ovarian follicle growth profiles, and twice daily thereafter to detect ovulation. Data were analyzed by ANOVA (LSD and Bartlett’s tests) and chi-square procedures. One cow (5mg EV group) lost the CIDR and was removed from all analyses. There was an effect of day (P&lt;0.0001) on CL diameter, but the effects of treatment (P=0.3), and the treatment-by-day interaction (P=0.1), were not significant. Follicular wave emergence occurred within 7d in 7/10 (70%) Control cows and 31/32 (97%; P&lt;0.04) EV-treated cows (one cow in late diestrus at the time of treatment did not respond to 1mg EV). Mean (±SD) interval from treatment to wave emergence was longer (P&lt;0.03) in cows treated with 5mg EV (4.8±1.2d) than in those treated with 1mg (3.2±0.9 days) or 2mg EV (3.4±0.8 days), while Control cows were intermediate (3.8±2.0 days). Although follicular wave emergence tended (P&lt;0.09) to be more synchronous in cows receiving EV, intervals from CIDR removal to estrus (P=0.7) and ovulation (P=0.8) did not differ among groups. Diameter of the dominant follicle was smaller (P&lt;0.04) at CIDR removal and tended to be smaller (P&lt;0.08) just prior to ovulation in the 5mg EV group (8.5±2.2 and 13.2±0.6mm, respectively) than in the Control (11.8±4.6 and 15.5±2.9mm, respectively) or 1mg EV (11.7±2.5 and 15.1±2.2mm, respectively) groups, with the 2mg EV group (10.7±1.5 and 14.3±1.7mm, respectively) intermediate. Diameter of the dominant follicle at CIDR removal was less variable (P&lt;0.01) in the 2 and 5mg EV groups than in the Control group and intermediate in the 1mg EV group. In summary, dose of EV affected follicular dynamics, interval to and synchrony of follicular wave emergence, and dominant follicle diameter at CIDR removal and just prior to ovulation in CIDR-treated cows. However, interval from CIDR removal to estrus and ovulation was not affected by treatment. Results suggest that a dose of 2mg EV may be most efficacious in synchronizing follicular wave emergence in CIDR-treated cows.

scholarly journals Peptide Regulators in the Ovarian Follicle

1981 ◽  
Vol 34 (6) ◽  
pp. 491 ◽  
Author(s):  
James M Hammond
Keyword(s):  
Luteinizing Hormone ◽  
Oocyte Maturation ◽  
Granulosa Cells ◽  
Follicular Fluid ◽  
Ovarian Follicle ◽  
Follicle Stimulating Hormone ◽  
Current Evidence ◽  
Follicular Growth ◽  
Maturation Inhibitor

Data generated within the last several years have shown that follicular fluid contains substances, presumably peptide in nature, which exert potentially important effects on granulosa cells and the oocyte. This review briefly summarizes the current evidence concerning the nature and importance of these putative regulators including the luteinization inhibitor, oocyte maturation inhibitor, inhibitors of the binding of luteinizing hormone and follicle stimulating hormone, stimulators of ornithine decarboxylase and intrafollicular peptides with gonadotrophin-releasing activity. Although the existence of such activities has been clearly demonstrated, the evidence for a regulatory role of these agents in the control of ovarian physiology is not compelling. However, their occurrence must now be taken into account in our attempts to understand the mechanism of follicular growth, differentiation and atresia.

scholarly journals 14OVARIAN FOLLICULAR DYNAMICS IN COWS TREATED WITH A CIDR, ESTRADIOL AND PROGESTERONE LATE IN THE ESTROUS CYCLE

2004 ◽  
Vol 16 (2) ◽  
pp. 129 ◽  
Author(s):  
J.P. Kastelic ◽  
M.G. Colazo ◽  
J.A. Small ◽  
D.R. Ward ◽  
R.J. Mapletoft
Keyword(s):  
Estrous Cycle ◽  
Ovarian Follicle ◽  
Animal Health ◽  
Beef Cows ◽  
Control Group ◽  
Dominant Follicle ◽  
Chi Square ◽  
Follicular Wave ◽  
Follicle Diameter ◽  
Follicular Dynamics

The objective was to characterize ovarian follicular dynamics in beef cows treated with a CIDR (Bioniche Animal Health; Belleville, Ontario, Canada) and an injection of estradiol-17β (E2), with or without progesterone (P4), late in the estrous cycle. Previously synchronized, non-lactating, crossbred beef cows (n=36) received a CIDR (Day 0) 16 to 18 days after ovulation and were randomly allocated to one of three treatment groups: no further treatment (Control, n=12), an injection of 5mg E2 (E2, n=12), or 5mg E2 plus 100mg P4 (E2P4, n=12; both from Sigma Chemical Co., St.Louis, MO, USA) i.m. in 2mL canola oil. On Day 7, CIDR were removed and cows received 500μg i.m. of cloprostenol (Estrumate, Schering Plough Animal Health, Pointe-Claire, Quebec, Canada). Ovaries were examined once daily by transrectal ultrasonography to detect ovarian follicle growth profiles, and determine the time of ovulation. Blood samples were taken daily for progesterone determination. Data were analyzed by ANOVA (LSD and Bartlett’s tests), Student’s t-test and chi-square procedures. Diameter of the CL and the dominant follicle, and progesterone concentration on Day 0 did not differ among groups (P=0.6; overall mean (±SD), 16.8±2.7mm, 14.1±2.0mm, and 1.5±1.9ngmL, respectively). Thirteen cows ovulated within 3 days of treatment (50% of E2- and E2P4-treated cows and 8.3% of Control cows; P=0.05); cows that ovulated had smaller CL diameters (15.2±1.7 v. 17.7±2.7mm; P&lt;0.004) and lower progesterone concentrations (0.4±0.2 v.2.1±2.2ngmL; P&lt;0.001) at the time of treatment. Follicular wave emergence occurred within 7 days in 4/12 Control cows, 10/12 E2-treated cows, and 10/12 E2P4-treated cows (P&lt;0.01). Although the interval from treatment to wave emergence did not differ among treatments (P=0.8; overall, 3.4±1.5 days), follicular wave emergence was more synchronous (P&lt;0.004) in the E2 group than in the Control or E2P4 groups. At CIDR removal, dominant follicle diameter was larger (P&lt;0.02) in the Control group (15.9±5.5mm) than in the E2 (11.9±1.8mm) or E2P4 (11.5±3.4mm)groups, but dominant follicle diameter was less variable (P&lt;0.003) in the E2 group than in the other two groups. Three cows did not ovulate after CIDR removal; two in the Control group and one in the E2P4 group. Interval to ovulation was shorter (P&lt;0.05) in the Control group (70.8±10.5h)than in the E2 (87.0±9.0h) or E2P4 (86.2±7.2h) groups, and the intervals to ovulation in cows that ovulated following treatment (91.0±8.0h) was longer (P&lt;0.001) than in those that did not (76.6±9.6h). In summary, treatment of cows with an estradiol-progesterone protocol late in the estrous cycle resulted in ovulation (50.0%), atresia (33.3%) or persistence (16.6%) of the dominant follicle present at that time. As length of follicular dominance and timing of ovulation were affected, fertility may be impaired following AI.

scholarly journals Role of low circulating FSH concentrations in controlling the interval to emergence of the subsequent follicular wave in cattle

Reproduction ◽  
2002 ◽  
pp. 475-482 ◽  
Author(s):  
OJ Ginther ◽  
DR Bergfelt ◽  
MA Beg ◽  
K Kot
Keyword(s):  
Dosage Regimen ◽  
Treated Group ◽  
Systemic Effect ◽  
Reciprocal Relationship ◽  
Control Group ◽  
Follicular Waves ◽  
Follicular Wave ◽  
Follicle Diameter ◽  
Stimulation Of

The intervals between emergence of follicular waves 1 (first wave of an oestrous cycle) and 2, and between the associated FSH surges (surges 1 and 2), were studied in control (n = 7) and recombinant bovine (rb)FSH-treated (n = 7) heifers. The expected start of the deviation in follicle diameter between the two largest follicles of wave 1 was defined as the day on which the largest follicle reached 8.5 mm (day 0). In the control heifers, circulating concentrations of FSH decreased and oestradiol increased between day 0 and day 1.5 or day 2.0 in a reciprocal relationship. The opposite reciprocal relationship between an FSH increase and an oestradiol decrease occurred during the next 3 days. This temporal result is consistent with a negative systemic effect of oestradiol on FSH at this time. rbFSH was administered in a dosage regimen that was expected to result in a similarity between FSH surge 2 in the rbFSH-treated group and surge 2 in the control group. On average, surge 2 and wave 2 occurred approximately 2 days earlier in the rbFSH-treated group than in the control group, and characteristics of the FSH surge and follicular wave were similar (no significant differences) between groups. These results support the hypothesis that low circulating FSH concentrations after the deviation in follicle diameter control the interval to emergence of the subsequent follicular wave. However, in one of seven rbFSH-treated heifers, the largest follicle from the apparent stimulation of rbFSH reached only 5.7 mm; therefore, the possibility of involvement of additional mechanisms cannot be dismissed.

scholarly journals Capillary angiogenesis and degeneration in bovine ovarian antral follicles

Reproduction ◽  
2003 ◽  
pp. 211-223 ◽  
Author(s):  
JY Jiang ◽  
G Macchiarelli ◽  
BK Tsang ◽  
E Sato
Keyword(s):  
Ovarian Follicle ◽  
Apical Part ◽  
Follicular Growth ◽  
Functional Changes ◽  
Antral Follicles ◽  
Theca Interna ◽  
Vascular Plexuses ◽  
Capillary Degeneration ◽  
Capillary Angiogenesis

Angiogenesis and capillary degeneration are both evident during ovarian follicle growth. However, the characteristics and distribution of thecal capillary proliferative and degenerative structures have not been fully defined. Indeed, the role of thecal microvasculature changes in follicular atresia is still a matter of debate. The present study examined the distribution of thecal capillary changes occurring during follicular growth and related the changes to capillary morphology (by scanning electron microscopy, SEM, on bovine ovarian corrosion casts) with the incidence of capillary apoptosis (TdT-mediated dUTP nick end-labelling, TUNEL) and follicular status (as confirmed by follicular fluid steroid concentrations). SEM demonstrated well-perfused vascular plexuses of small to large antral follicles with structural and functional changes to capillaries. Angiogenesis was evident mainly in the apical part of the inner capillary layer of medium follicles and the middle or basal part of the inner capillary layer of dominant follicles that exhibited high oestradiol:progesterone ratios. Degenerative capillaries were observed mainly in the outer vascular layers of small follicles, and in the inner and outer vascular layers of medium antral follicles. Although apoptotic structures were present only in the outer capillaries of the theca interna of morphologically healthy antral follicles, atretic follicles showed apoptotic structures in both the outer and inner thecal capillary layers. These results show that angiogenesis increases during bovine follicular growth and occurs unevenly in different inner theca regions of the follicles. The differential angiogenic and degenerative response of theca interna capillaries may reflect differences in the microenvironment of the follicles, which in turn determine the fate of the follicles (continued growth versus atresia).

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