Angela Baerwald

Characterization of Ovarian Follicular Wave Dynamics in Women

Abstract A wave phenomenon of ovarian follicular development in women has recently been documented in our laboratory. The objective of the present study was to characterize follicular waves to determine whether women exhibit major and minor wave patterns of follicle development during the interovulatory interval (IOI). The ovaries of 50 women with clinically normal menstrual cycles were examined daily using transvaginal ultrasonography for one IOI. Profiles of the diameters of all follicles ≥4 mm and the numbers of follicles ≥5 mm were graphed during the IOI. Major waves were defined as those in which one follicle grew to ≥10 mm and exceeded all other follicles by ≥2 mm. Minor waves were defined as those in which follicles developed to a diameter of <10 mm and follicle dominance was not manifest. Blood samples were drawn to measure serum concentrations of estradiol-17β, LH, and FSH. Women exhibited major and minor patterns of follicular wave dynamics during the IOI. Of the 50 women evaluated, 29/34 women with two follicle waves (85.3%) exhibited a minor-major wave pattern of follicle development and 5 women (14.7%) exhibited a major-major wave pattern. Ten of the 16 women with three follicle waves (62.5%) exhibited a minor-minor-major wave pattern, 3 women (18.8%) exhibited a minor-major-major wave pattern, and 3 women (18.8%) exhibited a major-major-major wave pattern. Documentation of major and minor follicular waves during the menstrual cycle challenges the traditional theory that a single cohort of antral follicles grows only during the follicular phase of the menstrual cycle.

A new model for ovarian follicular development during the human menstrual cycle

OBJECTIVE To evaluate changes in ovarian follicle dynamics during the human menstrual cycle to test the hypothesis that folliculogenesis occurs in a wave-like fashion. DESIGN Prospective longitudinal study. SETTING Healthy volunteers in an academic research environment. PATIENT(S) Fifty healthy women of reproductive age (range 19-43 years) with a history of regular menstrual cycles not taking medications known to interfere with reproductive function were evaluated. INTERVENTION(S) Transvaginal ultrasonography was performed daily for one interovulatory interval (IOI). MAIN OUTCOME MEASURE(S) Changes in the diameter and number of follicles > or =5 mm were evaluated. RESULT(S) Sixty-eight percent of women exhibited two waves of follicle development during the IOI and 32% exhibited three waves. Waves were characterized by an increase and subsequent decrease in the number of follicles > or =5 mm occurring in association with the growth of > or =2 follicles to > or =6 mm. A day effect and day by wave interaction were detected in the mean diameter of the largest three follicles and the number of follicles > or =5 mm. CONCLUSION(S) The follicular wave phenomenon in women provides a new model for ovarian function during the menstrual cycle and will improve our understanding of the ovarian response to fertility and hormonal contraceptive regimens.

Comparative Study of the Dynamics of Follicular Waves in Mares and Women

Abstract Deviation in growth rates of the follicles of the ovulatory wave begins at the end of a common growth phase and is characterized by continued growth of the developing dominant follicle (F1) and regression of the largest subordinate follicle (F2). Follicle diameters during an interovulatory interval were compared between 30 mares and 30 women, using similar methods for collecting and analyzing data. Follicles were tracked and measured daily by ultrasonography. Diameter at follicle emergence (mares, 13 mm; women, 6 mm) and the required minimal attained diameter for assessment of follicles (mares, 17 mm; women, 8 mm) were chosen to simulate the reported ratio between the two species in mean diameter of F1 at the beginning of deviation (mares, 22.5 mm; women, 10.5 mm). F1 emerged before F2 (P < 0.02) in each species, and the interval between emergence of the two follicles was similar (not significantly different) between species. Growth rate for F1 and F2 during the common growth phase was similar within species, and the percentage of diameter increase was similar between species. Proportionality between species in diameter of F1 at deviation (2.2 times larger for mares than for women) and at maximum preovulatory diameter (2.1 times larger) indicated that relative growth of F1 after deviation was similar between species. A predeviation follicle was identified in 33% of mares and 40% of women and was characterized by growth to a diameter similar to F1 at deviation but with regression beginning an average of 1 day before the beginning of deviation. The incidence of a major anovulatory wave preceding the ovulatory wave was not different between species (combined, 25%). Results indicated that mares and women have comparable follicle interrelationships during the ovulatory wave, including 1) emergence of F1 before F2, 2) similar length of intervals between sequential emergence of follicles within a wave, 3) similar percentage growth of follicles during the common growth phase, and 4) similar relative diameter of F1 from the beginning of deviation to ovulation. Similar follicle dynamics between mares and women indicate the mare may be a useful experimental model for study of folliculogenesis in women, with the advantage of larger follicle size.

Form and function of the corpus luteum during the human menstrual cycle

To characterize the growth and regression of the corpus luteum (CL) during an interovulatory interval (IOI) using serial transvaginal ultrasonography.

Large animal models for the study of ovarian follicular dynamics in women

Initial studies of the ovaries were based on postmortem anatomic descriptions, followed by histologic and endocrine approaches. The introduction of high-resolution ultrasonography provided a long-awaited tool to image the reproductive tissues in situ in both animals and humans. Critical studies of the characteristics and control of ovarian follicular and luteal dynamics in nonhuman primates, rodents, and domestic farm animals have involved frequent (i.e., daily or multiple times a day) blood sampling and ultrasonography. Studies of this nature in women are difficult, and often unethical to conduct. Differences in antral folliculogenesis between humans and animals appear to be more in detail rather than in essence, and may reflect differences in intrinsic physiology or merely differences in our ability to detect changes in a given species. In women, the presence of endometrial shedding and symmetric luteal and follicular phases are different from that observed during the estrous cycles of domestic farm animals but despite these differences, general similarities in antral follicular dynamics exist. A continuous pattern of antral follicle development was originally proposed in domestic livestock species; however, the use of frequent serial ultrasonography and simultaneous endocrine profiling in these animal species has resulted in a broad understanding of follicular wave dynamics. Follicular waves have now been described in every species in which this approach has been used, including humans. The relatively large diameters of antral follicles in cows and mares, compared with monkeys, sheep, and rodents provide greater feasibility for characterizing antral follicular dynamics ultrasonographically. While the use of large animal models has increased our understanding of ovarian function and provides the hypothetical basis for studies in women, differences in vocabulary, culture, and research methodologies has hampered knowledge translation. These differences represent a systemic impediment to a broad understanding of ovarian function and limits progress and innovation in the development of safer and more efficacious treatments for infertility and contraception.

Growth rates of ovarian follicles during natural menstrual cycles, oral contraception cycles, and ovarian stimulation cycles

OBJECTIVE To compare growth rates of ovarian follicles during natural menstrual cycles, oral contraception (OC) cycles, and ovarian stimulation cycles using standardized techniques. DESIGN Prospective, comparative, observational, longitudinal study. SETTING Healthy volunteers in research trials and infertility patients undergoing treatment at an academic institution. PATIENT(S) Women were evaluated during natural cycles (n = 50), OC cycles (n = 71), and ovarian stimulation cycles (n = 131). INTERVENTION(S) Serial transvaginal ultrasonography was performed to measure follicle diameter. Day-to-day growth and regression profiles of individual follicles were determined. Mean growth rates were calculated for ovulatory follicles. Mean growth and regression rates were calculated for anovulatory follicles. MAIN OUTCOME MEASURE(S) Follicle growth rate (in millimeters per day). RESULT(S) Mean follicular growth rate was greater during ovarian stimulation cycles (1.69 +/- 0.03 mm/day) compared to natural (1.42 +/- 0.05 mm/day) and OC cycles (1.36 +/- 0.08 mm/day). The interval from dominant follicle selection to ovulation was shorter during stimulation cycles (5.08 +/- 0.07 days) compared to natural cycles (7.16 +/- 0.23 days). CONCLUSION(S) Follicles grew faster during ovarian stimulation therapy compared to natural cycles or OC cycles. Greater follicular growth rates in stimulation cycles were associated with shorter intervals from selection to ovulation. The biologic effects of increased follicular growth rates and shorter intervals to ovulation on oocyte competence in women undergoing assisted reproduction remain to be determined.

Endometrial development in association with ovarian follicular waves during the menstrual cycle

Waves of ovarian follicular development during the menstrual cycle have recently been documented in our laboratory. The objective of this study was to test the hypothesis that ultrasonographically detectable changes in the endometrium during the menstrual cycle would differ between women with two vs. three waves of ovarian follicular development and among women with different major and minor wave patterns of follicle growth.

Detection of serum antimüllerian hormone in women approaching menopause using sensitive antimüllerian hormone enzyme-linked immunosorbent assays.

ObjectiveCurrent antimüllerian hormone (AMH) immunoassays are insufficiently sensitive to detect circulating AMH levels in ovulatory women approaching menopause. The aim of this study was to detect serum AMH levels across the menstrual cycle with age, using two new AMH enzyme-linked immunosorbent assay (ELISA) kits with increased sensitivity and differing specificity. MethodsSerum AMH levels were determined every 2 to 3 days across the interovulatory interval of menstrual cycles among women of early-mid reproductive age (18-35 y; n = 10) and late reproductive age (45-55 y; n = 17). Two highly sensitive AMH ELISAs (designated 24/32 and 24/37) with differing sensitivities were developed and applied to sera using a recombinant human pro-mature AMH preparation as reference. A third AMH ELISA (Gen II AMH ELISA kit; Beckman Coulter, Brea, CA) used was directed on mature-pro regions of AMH. ResultsAMH levels in all cycles were detectable with the 24/32 and 24/37 AMH ELISAs. AMH levels across the menstrual cycle were highly correlated (r = 0.98) between the 24/32 and 24/37 AMH ELISAs and the Gen II AMH ELISA (r = 0.94), but with large intracycle variations observed in older women. In late reproductive age, more than 95% of AMH values were detectable with the 24/32 and 24/37 AMH ELISAs, whereas only 36% of AMH values were detectable with the Gen II AMH ELISA. AMH levels were detected in cycles with lower antral follicle count and at a later age using the 24/32 and 24/37 AMH ELISAs compared with the Gen II AMH ELISA. AMH level correlated with antral follicle count in younger women, but not in older women. ConclusionsThe new 24/32 and 24/37 AMH ELISAs have the sensitivity to monitor ovarian follicle profiles in late reproductive age.

Systemic inflammation is associated with ovarian follicular dynamics during the human menstrual cycle.

Background Ovarian processes and the timing of ovulation are important predictors of both female fertility and reproductive pathology. Multiple waves of antral follicular development have been documented during the menstrual cycle in women. However, the mechanisms underlying the development of follicular waves and their clinical significance are not fully understood. The objective of this study was to examine the relationship between C-reactive protein (CRP) and follicular waves in healthy women. We wanted to determine whether follicular wave dynamics influence systemic inflammation, as ovarian activity increases local inflammatory processes and blood flow. We tested the hypothesis that women with 3 follicular waves would have higher CRP concentrations than those with 2 waves. We further hypothesized that a greater number of major waves (those with a dominant follicle) would be positively associated with CRP. Methods/Principal Findings Thirty-nine healthy women underwent daily transvaginal ultrasound examinations for one interovulatory interval, as part of an earlier study. Serum was collected every 3 days during the interovulatory interval (IOI). Enzyme-linked immunosorbent assays were conducted to quantify serum CRP concentrations. Women with 3 waves had higher average log CRP concentrations (n = 14, −0.43±0.35) over the IOI than those with 2 waves (n = 25, −0.82±0.47, p = 02). Average log CRP concentrations were greater in women with 3 (0.30±0.31) versus 1 (−0.71±0.55) or 2 (−0.91±0.47) major waves (p = 0.03). Greater average CRP over the IOI was attributed to greater CRP in the follicular, but not the luteal phase, of the IOI. Conclusions/Significance A greater number of total antral follicular waves, in particular major waves, corresponded to greater serum concentrations of CRP. These findings suggest that women with a greater number of follicular waves exhibit greater tissue remodeling and therefore greater local and systemic inflammation.

Ultrasound image attributes of human ovarian dominant follicles during natural and oral contraceptive cycles

BackgroundComputer-assisted analyses were used to examine ultrasound image attributes of human dominant ovarian follicles that developed during natural and oral contraceptive (OC) cycles. We hypothesized that image attributes of natural cycle follicles would quantitatively differ from those in OC cycles and that OC cycle follicles would possess image attributes indicative of atresia.MethodsDominant ovarian follicles of 18 clinically normal women were compared using transvaginal ultrasonography for the 7 days before ovulation during a natural cycle (n = 9) or the 7 days before peak estradiol in women using OC (n = 11). Follicles were analyzed using region and line techniques designed to compare the image attributes numerical pixel value (NPV), pixel heterogeneity (PH) and area under the curve (AUC).ResultsNPV was higher in OC cycle follicles with region analysis and tended to be higher with line analysis (p = 0.005 and p = 0.06, respectively). No differences were observed in two other image attributes (AUC and PH), measured with either technique, between natural and OC cycle follicles.ConclusionThe increased NPV value of OC cycle follicles and lack of differences in PH and AUC values between natural cycle and OC cycle follicles did not support the hypothesis that OC cycle follicles would show ultrasonographically detectable signs of atresia. Image attributes observed in OC cycle follicles were not clearly indicative of atresia nor were they large enough to preclude preovulatory physiologic status in OC cycle follicles.