252 THE ROLE OF INSULIN-LIKE GROWTH FACTOR 1 (IGF-1) IN DEVELOPMENT OF AN ESTROGEN-ACTIVE DOMINANT FOLLICLE DURING THE FIRST FOLLICULAR WAVE POSTPARTUM IN DAIRY COWS

2007 ◽  
Vol 19 (1) ◽  
pp. 242
Author(s):  
C. Kawashima ◽  
N. Sudo ◽  
C. Amaya Montoya ◽  
E. Kaneko ◽  
M. Matsui ◽  
...  
Keyword(s):  
Dairy Cows ◽  
Repeated Measures ◽  
Follicular Development ◽  
High Plasma ◽  
T Test ◽  
Dominant Follicle ◽  
High Concentration ◽  
Follicular Wave ◽  
Follicle Diameter ◽  
High Level

Recent studies have shown that IGF-1 is a crucial factor for ovarian follicular development in mammals. In postpartum (pp) dairy cows, plasma IGF-1 and estradiol (E2) levels in ovulatory cows at the first follicular wave pp are higher than in anovulatory cows. However, the plasma IGF-1 profile in an ovulatory or anovulatory dominant follicle (DF), which have different E2 production, at the first follicular wave pp have not yet been elucidated. Thus, we investigated the changing profile of plasma IGF-1 levels during first follicular wave pp. In 22 multiparous Holstein cows, blood samples were obtained 2 times/week from 4 weeks prepartum to 3 weeks pp, and the first follicular wave was monitored by ultrasound 2 times/week from 7 days pp to ovulatory phase. Detailed IGF-1 profiles in blood were determined during DF growth and maturation 4 times/day from 10 days pp to 7 days after the first ovulation in 5 ovulatory cows and to 20 days pp in 4 anovulatory cows; the data were analyzed by repeated measures ANOVA, and Student's t-test. There was no interaction between groups and time within the prepartum or the pp period. The ovulatory cows (n = 13/22) with an estrogen-active dominant (EAD: high plasma E2 level with peak) follicle showed higher IGF-1 levels than anovulatory cows (n = 9/22) with an estrogen-inactive dominant (EID: low plasma E2 level without peak) follicle during the prepartum (117 � 8 vs. 91 � 5 ng mL-1; P < 0.05) and the pp (91 � 4 vs. 64 � 4 ng mL-1; P < 0.001) period. Especially noteworthy, during the first follicular wave pp in ovulatory cows, the plasma IGF-1 levels were maintained at a high level until E2 levels increased, followed by an LH surge. We observed that the EAD follicle in ovulatory cows ovulated. To further examine the IGF-1 system in the intra-follicular environment, we used the EAD and EID follicles from ovaries of dairy cows obtained at a slaughterhouse. The EAD and EID follicles were classified on the basis of follicle diameter and E2 concentrations in follicular fluid (FF). The significant differences of factors between EAD and EID were analyzed by Student's t-test. The expression of IGF-1 mRNA was not detected in follicular cells in either EAD and EID, suggesting that IGF-1 in FF is mainly derived from liver. The free IGF-1 levels in FF in EAD (4.8 � 0.5 ng mL-1) were higher than those in EID (2.7 � 0.1 ng mL-1; P < 0.05). In addition, the expression of type 1 IGF receptor (IGFR-1) mRNA in EAD was higher than hat in EID (P < 0.0001). From the results of the present study, it is apparent that the EAD follicle during the first follicular wave pp in ovulatory cows sufficiently expressed IGFR-1, and a liver-derived IGF-1 stimulates E2 production in the follicle to ovulate. In conclusion, our data suggest that a high concentration of IGF-1, secreted from the liver, during the peripartum period may be one of important factors for the appearance of an ovulatory follicle during the first follicular wave pp cows.

scholarly journals Nutritional Factors That Regulate Ovulation of the Dominant Follicle During the First Follicular Wave Postpartum in High-producing Dairy Cows

2012 ◽  
Vol 58 (1) ◽  
pp. 10-16 ◽  
Author(s):  
Chiho KAWASHIMA ◽  
Motozumi MATSUI ◽  
Takashi SHIMIZU ◽  
Katsuya KIDA ◽  
Akio MIYAMOTO
Keyword(s):  
Dairy Cows ◽  
Dominant Follicle ◽  
Nutritional Factors ◽  
Follicular Wave

scholarly journals Follicular dynamic and repeatability of follicular wave development in Peranakan Ongole (PO) cattle

2016 ◽  
Vol 21 (1) ◽  
pp. 26 ◽  
Author(s):  
Muhammad Imron ◽  
Iman Supriatna ◽  
. Amrozi ◽  
Mohamad Agus Setiadi
Keyword(s):  
Bos Taurus ◽  
Research Result ◽  
Bos Indicus ◽  
Follicular Development ◽  
Wave Pattern ◽  
Follicular Wave ◽  
Follicle Diameter ◽  
Wave Patterns ◽  
The Difference ◽  
Follicular Dynamics

<p class="abstrak2">Superovulation treatment on PO cattle (Bos indicus) was less responsive compared to Bos taurus breed. It might due to the difference of their follicular dynamic. This study was conducted to investigate the follicular dynamics and its repeatability in PO cattle. Follicular dynamics observations conducted on 9 cows trough ultrasound scanning every day. Observations of wave patterns repeatability were performed in 6 cows which its wave pattern already known on the next consecutive IOI.  Research result indicated that PO cattle had 3 (66%) and 4-waves (34%) pattern. The first wave of 3 and 4-waves pattern emerged on day -0.4+0.9 and 1.4+1.1 respectively.  The second wave of 3 and 4-wave pattern emerged on day 9.8+1.5 and 7.4+1.9 respectively.  The pattern of 3 waves has a longer follicle dominant duration (11.6+1.5 day) in the first wave of estrous cycle, compared with 4 waves pattern (10+2.92 and 7+1.00 day respectively). The growth rate of dominant follicle was not different significantly between the 3 and 4-waves pattern (0.87+0.23 and 0.94+0.25 mm/day respectively). Similarly, ovulatory follicle diameter between 3 and 4-waves pattern was also not different significantly (12.24+12.34 and 12.30+12.23 mm respectively). Observation of wave patterns repeatability in 6 PO cows indicated that PO cattle had high repeatability in follicular wave pattern (0.88) and the number of growing follicle was 0.91.  This study resulted data for dynamic of follicular development, wave pattern, its repeatability which be expected to design the protocol of superovulation treatment or other reproduction technologies based on follicular dynamic to improve its result in PO cattle.</p><p> </p>

scholarly journals Relationship between metabolic hormones and ovulation of dominant follicle during the first follicular wave post-partum in high-producing dairy cows

Reproduction ◽  
2007 ◽  
Vol 133 (1) ◽  
pp. 155-163 ◽  
Author(s):  
Chiho Kawashima ◽  
Saori Fukihara ◽  
Mayumi Maeda ◽  
Etsushi Kaneko ◽  
Carlos Amaya Montoya ◽  
...  
Keyword(s):  
Blood Flow ◽  
Dairy Cows ◽  
Ovarian Function ◽  
Post Partum ◽  
Plasma Concentrations ◽  
Reproductive Hormones ◽  
Follicular Growth ◽  
Dominant Follicle ◽  
Follicular Wave ◽  
Igf I

Recent studies suggest that IGF-I is a crucial regulatory factor in follicular growth during earlypost-partumperiod. The aim of the present study was to determine in detail the changing profiles of metabolic and reproductive hormones in relation to ovulation of the dominant follicle (DF) of the first follicular wavepost-partumin high-producing dairy cows. Plasma concentrations of related hormones in 22 multiparous Holstein cows were measured from 4 weeks pre-partum to 3 weekspost-partum, and the development of DF was observed with colour Doppler ultrasound. Thirteen cows showed ovulation by 15.2 dayspost-partum. Anovulatory cows showed higher GH and lower IGF-I levels than those in ovulatory cows during the peri-partum period. Each DF developed similarly, and a clear blood flow in the follicle wall was observed despite ovulation or anovulation. In addition, detailed endocrine profiles were analyzed in 9 out of the 22 cows. Five cows showed an increase in plasma oestradiol-17β (E2) with follicular growth followed by E2 peak, LH surge and ovulation. In these cows, plasma IGF-I concentrations remained high until 10 dayspost-partumfollowed by a gradual decrease. Subsequently, the insulin level increased together with the E2 peak towards ovulation. These profiles were not observed in anovulatory cows. In conclusion, our data strongly support the concept that IGF-I and insulin represent ‘metabolic signals’ of the resumption of ovarian functionpost-partumin high-producing dairy cows. Moreover, we provide the first visual evidence that both ovulatory and anovulatory DFs of the first follicular wavepost-partumare similarly supplied with active blood flow.

36 FOLLICULAR DYNAMICS IN PROLIFIC SHEEP: PGF-BASED ESTRUS SYNCHRONIZATION

2010 ◽  
Vol 22 (1) ◽  
pp. 176
Author(s):  
L. Proctor ◽  
D. Tutt ◽  
D. Olliver ◽  
S. Galloway ◽  
J. L. Juengel ◽  
...  
Keyword(s):  
Animal Health ◽  
T Test ◽  
Corpora Lutea ◽  
Follicular Wave ◽  
Follicle Diameter ◽  
Array Transducer ◽  
Significant Difference ◽  
Preovulatory Follicles ◽  
Student’S T ◽  
Follicular Dynamics

A study was designed to compare the effect of a prostaglandin-based synchronization protocol on ovarian follicular dynamics in sheep with the FecB (Booroola) mutation. Forty dry Romney sheep (57.6 ± 7.3 kg; 6.1 ± 1.1 years) were randomly selected from both Invermay Booroola (BB; n = 20) and commercial (non-FecB carriers, ++; n = 20) flocks. All ewes had their estrous cycles synchronized with 2 i.m. injections of PGF (150 μg of cloprostenol, Estrumate, Schering-Plough Coopers Animal Health Ltd., New Zealand) administered 7 days apart. Ewes were monitored by transrectal ultrasonography (Aloka 900-SSD and a 7.5-MHz linear-array transducer, Aloka, Tokyo, Japan) daily from Day -2 to the day of ovulation. Data were analyzed by Student’s t-test or Wilcoxon Rank Sum test. Variances were compared with Barlett’s test. Paired t-test compared the number of preovulatory follicles in each genotype after PGF treatments and intervals from PGF to ovulation after PGF. Data are presented as mean (± SEM). The number of corpora lutea (CL) and total CL area at the time of the first and second PGF treatment were 4.4 ± 0.6; 5.7 ± 1.4 and 672.1 ± 133.5 mm2; 999.0 ± 145.9 mm2 in the BB and 2.1 ± 0.2; 2.1 ± 0.5 and 342.3 ± 60.7 mm2; 401.3 ± 68.6 mm2 in ++ ewes, respectively. These 2 variables were higher (P < 0.01) at both PGF injections in the BB than in the ++ ewes, except the CL area at the time of first PGF treatment (P = 0.15). The largest follicle diameter at the time of the first and second PGF treatments was smaller (P < 0.003) in BB (4.1 ± 0.3 mm; 3.5 ± 0.2 mm) than in ++ (5.3 ± 0.3 mm; 5.8 ± 0.1 mm) ewes. The median and mean number of follicles that ovulated after the first and second PGF treatment were higher (P < 0.0001) in BB (6 & 7; 5.7 ± 0.3; 6.9 ± 0.3; difference = 1.2 ± 0.4; P < 0.003) than in the ++ (2 & 2; 2.1 ± 0.1; 2.1 ± 0.1) sheep. The luteal area at the time of first and second PGF in both BB and ++ did not differ (P = 0.3). The intervals from the first and second PGF to the respective ovulations did not differ (P > 0.61) between BB (3.4 ± 0.2; 3.0 ± 0.3d) and ++ (3.5 ± 0.2d; 3.0 ± 0.1d) ewes. However, interval from the second PGF to ovulation was more variable (P = 0.002) in the BB than in the ++ ewes. Data of both groups were combined and a mean significant difference of 0.6 ± 0.2d (P < 0.003) was found between the first and second PGF-to-ovulation intervals. The interval from the first PGF to emergence of the next follicular wave was shorter (P < 0.02) and more variable (P < 0.03) in the BB (2.7 ± 0.4d) than in the ++ (3.5 ± 0.2 d) group. Preovulatory follicles were smaller in Booroola, but higher in number, than in ++ ewes, whereas the luteal area was similar. Within the BB ewes, the higher number of follicles that ovulated after the second PGF than after the first injection may be due to a higher follicular response to an elevated rebound in circulating FSH after the first PGF. A high number of growing follicles of the first follicular wave may also have contributed to this event. These findings warrant further research aimed at the study of the interaction between FSH and follicle dynamics in estrus synchronized sheep carrying the FecB mutation.

13 Pre-synchronization by Induction of a Dominant Follicle Using a Progesterone Device in a GnRH-Based-Ovulation Synchronization Protocol in Lactating Dairy Cows

2018 ◽  
Vol 30 (1) ◽  
pp. 146
Author(s):  
M. P. Bottino ◽  
L. A. C. L. DaSilva ◽  
L. M. S. Simoes ◽  
G. Santos ◽  
I. Y. H. Martinez ◽  
...  
Keyword(s):  
Sustained Release ◽  
Dairy Cows ◽  
Prostaglandin F2α ◽  
Follicular Development ◽  
Experimental Period ◽  
Ovulation Rate ◽  
Dominant Follicle ◽  
Lactating Dairy Cows ◽  
Intravaginal Device ◽  
Synchronization Protocol

The objective was to compare a pre-synchronization protocol by induction of a dominant follicle using a progesterone intravaginal device before an Ovsynch protocol (Presynch) with Double-Ovsynch in lactating dairy cows. Lactating Bos indicus × Bos taurus crossbred cows (n = 440) were randomly allocated to 1 of 2 treatments (all IM injections): (1) Double-Ov (n = 228): GnRH (Day –17), prostaglandin F2α (PGF2α) 7 days later (Day –10) and gonadotropin-releasing hormone (GnRH) 3 days later (Day –7) followed by an Ovsynch protocol 7 days later (GnRH on Day 0, PGF2α on Day 7, GnRH on Day 9); (2) Presynch (n = 212): insertion of a sustained release progesterone intravaginal device (Day –10), 10 days later (Day 0), an Ovsynch protocol was initiated with progesterone device withdrawal on Day 7. All cows were artificially inseminated 15 to 20 h after the second GnRH injection of the Ovsynch protocol and were pregnancy checked by ultrasonography 30 and 60 days later. On a subsample (n = 102), ultrasonography was performed on Days 0, 7, 9, and 24 of the experimental period. On another subsample (n = 42), blood samples for progesterone analysis were taken on Days 0, 7, and 24. There were no differences between pre-synchronization methods on synchronization parameters [presence of a follicle >12 mm on D0, Double-Ov 94.2% (49/52) and Presynch 92.0% (46/50); P = 0.66], follicular diameter on the 1st GnRH (Double-Ov 17.2 ± 0.7 mm and Presynch 18.6 ± 0.9 mm; P = 0.28), ovulation rate to the 1st GnRH [Double-Ov 86.3% (44/51) and Presynch 81.2% (39/48); P = 0.50], synchronization rate [Double-Ov 84.6% (44/52) and Presynch 86.0% (43/50); P = 0.84], follicular diameter on the 2nd GnRH (Double-Ov 17.5 ± 0.6 mm and Presynch 18.0 ± 0.5 mm; P = 0.48), ovulation rate to the 2nd GnRH [Double-Ov 90.9% (40/44) and Presynch 86.0% (37/43); P = 0.48] and CL diameter on Day 24 (Double-Ov 27.9 ± 0.7 mm and Presynch 29.4 ± 0.9 mm; P = 0.19). Corpus luteum presence on Day 0 was different (P = 0.03) between treatments [Double-Ov 57.7% (30/52) and Presynch 36.0% (18/50)]. Moreover, there was no difference (P = 0.85) between pregnancy rates on Day 30 [Double-Ov 39.0% (89/228) and Presynch 40.1% (85/212)] or Day 60 after AI [Double-Ov 34.8% (79/227) and Presynch 38.7% (82/212); P = 0.41] and gestational loss between 30 and 60 days after AI [Double-Ov 7.9% (7/88) and Presynch 3.5% (3/85); P = 0.13]. Proportion of cows with P4 <1 ng mL−1 on Day 0 was similar between treatments [Double-Ov 13.6% (3/22) v. Presynch 5.0% (1/20); P = 0.37]. Likewise, the proportion of cows with P4 >1 ng mL−1 on Day 7 [Double-Ov 77.3% (17/22) v. Presynch 95.0% (19/20); P = 0.14] and P4 concentration on Day 24 (Double-Ov 4.7 ± 0.6 v. P4-Ov 5.9 ± 0.9; P = 0.84) were similar between treatments. In conclusion, pre-synchronization by induction of follicular persistence using a sustained-release progesterone device before Ovsynch yielded similar results to the Double-Ovsynch protocol on follicular development and regression patterns and on the fertility of lactating dairy cows.

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.

Identification of novel genes associated with dominant follicle development in cattle

2007 ◽  
Vol 19 (8) ◽  
pp. 967 ◽  
Author(s):  
Anna E. Zielak ◽  
Niamh Forde ◽  
Stephan D. E. Park ◽  
Fiona Doohan ◽  
Paul M. Coussens ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
Follicular Development ◽  
Intracellular Signalling ◽  
Follicle Development ◽  
The Novel ◽  
Dominant Follicle ◽  
Novel Genes ◽  
Follicular Wave ◽  
New Genes ◽  
Follicle Selection

Follicle development is regulated by the interaction of endocrine and intrafollicular factors, as well as by numerous intracellular pathways, which involves the transcription of new genes, although not all are known. The aim of the present study was to determine the expression of a set of unknown genes identified by bovine cDNA microarray analysis in theca and granulosa cells of dominant and subordinate follicles, collected at a single stage of the first follicular wave using quantitative real-time polymerase chain reaction. Differences were further examined at three stages of the follicular wave (emergence, selection and dominance) and bioinformatics tools were used to identify these originally unknown sequences. The suggested name function and proposed role for the novel genes identified are as follows: MRPL41 and VDAC2, involved in apoptosis (dominant follicle development); TBC1D1 stimulates cell differentiation (growth associated with dominant follicle selection and development); STX7, promotes phagocytosis of cells (subordinate follicle regression); and SPC22 and EHD3, intracellular signalling (subordinate follicle regression). In conclusion, we have identified six novel genes that have not been described previously in ovarian follicles that are dynamically regulated during dominant follicle development and presumably help mediate intracellular signalling, cell differentiation, apoptosis and phagocytosis, events critical to follicular development.

scholarly journals 223DEVELOPMENTAL PATTERN OF SMALL (1-3mm) ANTRAL FOLLICLES IN THE BOVINE OVARY

2004 ◽  
Vol 16 (2) ◽  
pp. 233
Author(s):  
R.S. Jaiswal ◽  
J. Singh ◽  
G.P. Adams
Keyword(s):  
Repeated Measures ◽  
Wave Pattern ◽  
Developmental Pattern ◽  
Dominant Follicle ◽  
Antral Follicles ◽  
Follicular Wave ◽  
Statistical Analysis System ◽  
The Future ◽  
Bovine Ovary ◽  
Analysis System

Knowledge about the developmental pattern of small follicles (&lt;4mm) will be crucial to understanding the endogenous control of folliculogenesis and to developing methods to control it for clinical purposes. This study was designed to characterize the developmental pattern of 1–3mm follicles and to determine, retrospectively, the stage at which the future dominant follicle first attains a size advantage among follicles in the cohort. In Experiment 1, the ovaries of Hereford-cross heifers (n=18) were examined daily by high resolution transrectal ultrasonography for one natural interovulatory interval to evaluate changes in the number of 1–3-mm follicles in relation to the wave pattern of follicles ≥4mm. Interovulatory interval was divided into 2- and 3-wave based on number of waves exhibited by heifers. In Experiment 2, the ovaries of Hereford-cross cows (n=9) were examined every 6h from Day 5 to Day 13 (Day 0=ovulation) to monitor precisely the diameter changes of individual follicles ≥1mm during emergence of the second follicular wave. Data were analyzed by Proc. Mixed procedure for repeated measures (Littell RC et al., 2000 Stat in med 19, 1793–1819) in the Statistical Analysis System software package (SAS version 8.2 for MS Windows;; 2002 SAS Institute Inc. Cary, NC, USA). Results of Experiment 1 revealed a day effect (P&lt;0.05) on the number of small (1–3mm) follicles, with a peak (P&lt;0.05) 1 or 2 days before wave emergence (defined as the day the dominant follicle was first detected at 4mm), followed 3 to 4 days later by a peak (P&lt;0.05) in the number of large follicles (≥4mm). There was an inverse relationship between the number of small and large follicles during Wave 1 (r=−0.66; P=0.05) and Wave 2 (r=−0.62; P=0.04) in 2-wave interovulatory intervals. Similarly, an inverse relation was detected between the number of small and large follicles for Wave 1 (r=−0.79; P=0.01) and Wave 3 (r=−0.90; P&lt;0.01) but not for Wave 2 (r=−0.57; P=0.14) in 3-wave interovulatory intervals. The number of 1–3-mm follicles detected in anovulatory waves did not differ (P=0.53) between 2- versus 3-wave interovulatory intervals;; however, a difference (P&lt;0.05) was observed between anovulatory and ovulatory waves in 3-wave interovulatory intervals but not (P=0.63) in 2-wave interovulatory intervals. Experiment 2 permitted the identification of the future dominant follicle at a diameter of 1mm and its emergence at 6–12h earlier than the largest subordinate follicle (P&lt;0.01). Emergence of the future dominant (r=0.71; P=0.05) and 1st subordinate (r=0.78; P=0.02) follicles was temporally associated with a wave-eliciting rise in circulating concentrations of FSH. Growth rate of the dominant and the 1st subordinate follicle differed (P&lt;0.01) from 2nd subordinate follicle at 84h after their detection at 1mm. It was concluded that small antral follicles (1–3mm) develop in a wave-like manner, and apparent selection of the dominant follicle was manifest much earlier than previously documented.

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