| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Minireview |
a Department of Animal Health and Biomedical Sciences, University of Wisconsin, Madison, Wisconsin 53706
 |
ABSTRACT |
|---|
 TOP ABSTRACT INTRODUCTIONDEVIATION AND THE SIZE...FOLLICLE-STIMULATING...FOLLICULAR FSH SUPPRESSANTSROLE OF LHINTRAFOLLICULAR AND CELLULAR...REFERENCES |
|---|
estradiol, follicle, follicle-stimulating hormone, growth factors, luteinizing hormone
|
INTRODUCTION |
|---|
|
TOPABSTRACTINTRODUCTIONDEVIATION AND THE SIZE...FOLLICLE-STIMULATING...FOLLICULAR FSH SUPPRESSANTSROLE OF LHINTRAFOLLICULAR AND CELLULAR...REFERENCES |
|---|
This minireview considers cattle and horses as comparative research models for humans. Cattle and horses have similar follicle-selection characteristics, despite an approximately 2.5-fold greater diameter of the follicles in horses throughout a follicular wave (e.g., preovulatory diameter, 40 versus 16 mm). Limited initial reports suggest the presence of similar selection characteristics during the ovulatory wave in humans [2–4], with follicles a few millimeters larger than in cattle (e.g., preovulatory diameter, 21 mm). This minireview integrates the research findings from cattle, horses, and humans. The report will be focused on the mechanism whereby one follicle establishes dominance over other follicles in a relatively short time (e.g., in an average of <8 h in cattle [5]). Earlier reviews can be consulted for broader information in farm species [5–10] and humans [11–13].
|
DEVIATION AND THE SIZE ADVANTAGE |
|---|
|
TOPABSTRACTINTRODUCTIONDEVIATION AND THE SIZE...FOLLICLE-STIMULATING...FOLLICULAR FSH SUPPRESSANTSROLE OF LHINTRAFOLLICULAR AND CELLULAR...REFERENCES |
|---|
The beginning of observed deviation in the diameter profiles of individual follicles occurs at the ultrasound examination preceding the first examination with an apparent change in diameter differences between the two largest follicles [14]. The beginning of expected deviation can be based on diameters obtained in previous studies of observed deviation and is used for experimental procedures that may interfere with or terminate deviation. Averaged over several reports [5], observed deviation for the first anovulatory wave in heifers began when the largest follicle was a mean of 8.5 mm and for the ovulatory wave in mares was a mean of 22.5 mm. In women, reports on the growth of follicles are consistent with a deviation phenomenon during the ovulatory wave [2–4]. However, deviation has not been described, specifically. In one study [2], the dominant or ovulatory follicle was first recognized by its larger diameter when the two largest follicles were means of 9.9 and 5.9 mm, respectively. The 4-mm difference suggests that presumed deviation would have begun at least 1 day earlier or between 8 and 9 mm. Two examples of ovulatory waves in women [3] and in each of the other two species and our judgment on the beginning of deviation are shown (Fig. 1). Mean follicle-diameter profiles normalized to deviation (heifers) and emergence (mares) are depicted (Figs. 2 and 3).
|
|
Between emergence and deviation in heifers [14] and mares [16], the growth rates of the two largest follicles seem parallel in about 50% of individual waves; examples of the variation in growth profiles have been published [6, 14, 16]. The imprecision in measuring the sometimes irregularly shaped follicles [1] can be expected to contribute to fluctuations in data growth profiles. In addition, the time used in completing deviation varies, as suggested by variation in the interval between the beginning of deviation and terminated growth of the subordinate follicles. For these reasons, the beginning of deviation is indistinct in about 20% of waves (unpublished results). The follicle that first reached 8.0 mm in heifers (examinations every 8 h) and 20.0 mm in mares (examinations every day) became the dominant follicle in 90% of 51 waves and 93% of 29 waves, respectively. These diameters occurred on average at the examination before the beginning of deviation. The corresponding data when the largest follicle reached 7.0 and 17.5 mm (approximately 1 day earlier) were 71% and 81%.
The difference in diameter between the two largest follicles at the end of the common-growth phase (beginning of deviation) is postulated [14] to allow the largest follicle to establish dominance before the next largest follicle can reach a similar diameter (Fig. 4). In this regard, the mean difference in diameter between the two follicles provides an apparent indication of the mean time required for the establishment of deviation (heifers, 0.5 mm, equivalent to 8 h of growth [15]; mares, 3 mm, equivalent to 1 day of growth [16]). We know of no other adequately supported interpretation, other than size or developmental advantage, that could account for the ability of one follicle to rapidly establish dominance. Despite this simple assumption, the mechanism for utilization of the size advantage in the establishment of deviation is complex.
|
|
FOLLICLE-STIMULATING HORMONE:FOLLICLE-COUPLING HYPOTHESIS |
|---|
|
TOPABSTRACTINTRODUCTIONDEVIATION AND THE SIZE...FOLLICLE-STIMULATING...FOLLICULAR FSH SUPPRESSANTSROLE OF LHINTRAFOLLICULAR AND CELLULAR...REFERENCES |
|---|
|
|
The FSH:follicle relationship changes from multiple- to single-follicle coupling at the beginning of deviation (Fig. 5). The coupling from the single follicle to FSH has been demonstrated by ablating the largest follicle at the expected beginning of deviation; FSH concentrations increased soon after ablation in heifers (Fig. 6) and mares [20]. An FSH increase also occurs in women after ablation of the dominant follicle [21]. The coupling in the opposite direction (from FSH to the single follicle) has been demonstrated in heifers. Experimentally depressing the FSH concentrations below the prevailing concentrations at the expected beginning of deviation interfered with growth of the largest follicle [18, 22]. It was concluded that the more-developed largest follicle not only withstood but also required the low FSH concentrations associated with deviation. Experimental prevention of the postdeviation FSH decline suggested that the FSH concentrations at the beginning of deviation were already below the requirements of the smaller follicles and the continued FSH decline usually was not needed for the continuation of deviation (unpublished results). Consistent with this result, the smaller follicles were not further inhibited when FSH was experimentally reduced below the concentrations in controls at the expected beginning of deviation [18]. These findings indicated that a developmental change occurs in the largest follicle by the beginning of deviation so that it is responsive to a concentration of FSH that is inadequate for the smaller follicles, thereby heralding the beginning of deviation. In this regard, cultured granulosa cells from women are more responsive to low doses of FSH when obtained from larger follicles (>8 mm [12]). In monkeys, mature follicles thrive in the presence of FSH concentrations that are too low to support less-mature follicles [23].
|
The tightness of the FSH/follicle coupling has been demonstrated in heifers by the following results: 1) an FSH suppressant given near the middle of the FSH decline reduced both the FSH concentration and diameter of the three largest follicles by 8 h after treatment [18], 2) an FSH suppressant given at the expected beginning of deviation reduced the diameter of the largest follicle by 6 h after the experimental reduction in FSH concentrations [18, 22, 24], and 3) ablation of the largest follicle at expected deviation was followed by an increase in FSH concentrations beginning 4 or 5 h after ablation [18, 24]. These results satisfied the postulated minimal interval of <8 h in heifers from the beginning of deviation to the establishment of deviation (Fig. 4) and represent the basis of the FSH/follicle coupling hypothesis.
The coupling hypothesis is consistent with an earlier interpretation that the decline in the wave-stimulating FSH surge plays a role in follicle selection in cattle [25]; exogenous FSH interfered with selection. The hypothesis is compatible with the threshold/window terminology developed for humans [12]. That is, the duration (window) that FSH concentrations of the wave-stimulating surge are above a threshold level is short for development of a single large follicle and prolonged for development of multiple large follicles. Exogenous FSH widens the window and thereby induces the growth of multiple dominant follicles (10 mm or larger [17]). The coupling hypothesis differs from a proposal [26] that selection occurs in humans when the follicles are 2–4 mm. These diameters are equivalent to the time of an FSH increase in women [2, 12, 27], presumably at the stimulation of a wave. The period of the FSH increase was likened to a gate through which only the selected follicle can pass because it alone is at a favorable developmental stage [26]. In contrast, according to the FSH:follicle-coupling hypothesis, selection occurs days later from the continued close dependency of the follicles on FSH, resulting in rapid deprivation of the less-developed smaller follicles when the FSH concentrations have decreased to a critical level at the beginning of deviation.
|
FOLLICULAR FSH SUPPRESSANTS |
|---|
|
TOPABSTRACTINTRODUCTIONDEVIATION AND THE SIZE...FOLLICLE-STIMULATING...FOLLICULAR FSH SUPPRESSANTSROLE OF LHINTRAFOLLICULAR AND CELLULAR...REFERENCES |
|---|
Certain forms of inhibin are involved systemically in deviation through a suppressant action on circulating FSH concentrations. In this report, the term inhibin will be used when the specific form is not known. An FSH-suppressing activity of bovine and equine follicular fluid has been demonstrated by an increase in FSH concentrations after ablation of follicles [5] and a decrease in FSH after treatment with a proteinaceous fraction of follicular fluid [22]. In addition, administration of an inhibin antiserum increased plasma FSH concentrations and increased the number of large follicles and ovulations in both species [5]. In cattle, circulating concentrations of total inhibin were reported to increase concurrently with the emergence of waves [28] and with an increase in estradiol [29]. The time of an estradiol increase is equivalent to the beginning of deviation [30]. Treatment with an anti-inhibin 5 days after estrus (apparently after the beginning of deviation) resulted in an increase in FSH [29], suggesting that inhibin plays a role in the continued postdeviation FSH decrease in cattle.
In mares, total inhibin concentrations during the estrous cycle increase in the circulation at the time FSH concentrations are declining [31–33]. In a recent study (unpublished results), it was concluded that the first 2 days of the FSH decrease was caused by inhibin, based on the positive relationship between the number of experimentally retained follicles and the extent of the increase in circulating total inhibin concentrations and the corresponding decrease in FSH (Fig. 7). Near the expected day of deviation, total inhibin remained at elevated concentrations and likely contributed to the continuing FSH decline. In this regard, treatment with serum containing inhibin antibodies on the day the largest follicle was 20 mm and on the next day resulted in an increase in the number of 30-mm follicles [34]. A 20-mm largest follicle is close to a mean of 22.5 mm at the beginning of deviation [16]. The results therefore suggested that inhibin continues to be a postdeviation FSH suppressant in mares.
|
In women, circulating inhibin-A and inhibin-B have different concentration profiles during the menstrual cycle [27]. A rise in inhibin-B began near the peak of the FSH surge [27] and was high during the early follicular growth phase [4, 27]. In contrast, inhibin-A was low during the early growth phase [27] and began to increase approximately as estradiol increased or the largest follicle was first recognized by its largest diameter [4, 17]. Using the terminology of this minireview, inhibin-B apparently increased during the common-growth phase and inhibin-A near or after the beginning of presumptive deviation.
Estradiol
In cattle, estradiol begins to increase in the circulation at the beginning of deviation [15, 30]. Experimentally increasing or decreasing the circulating estradiol concentrations at the expected beginning of deviation resulted in a decrease or increase, respectively, in FSH concentrations (Fig. 6), indicating a functional relationship between the two hormones. The largest follicle at the expected beginning of deviation (8.5 mm) had greater FSH-suppressing power than the largest follicle at 7.5 mm [18]. The added capacity of an 8.5-mm follicle for suppressing systemic FSH may reflect the combined action [35, 36] of an inhibin and estradiol.
In mares, estradiol begins to increase in the circulation the day before the beginning of deviation [37]. Thus, on a temporal basis, increased estradiol apparently does not contribute to the FSH decline until the day before deviation. Ablation of the largest follicle at the expected beginning of deviation prevented the continuing estradiol increase and resulted in an associated FSH increase [20]; an FSH increase did not occur when the second-largest follicle was ablated. Both estradiol and inhibins would be lost upon ablation of the largest follicle and a decrease in either or both could account for the resulting increase in FSH.
In women, an increase in circulating estradiol occurs at about the time the dominant follicle is first identifiable by its larger diameter (>9 mm [4, 12, 38]). In monkeys, exogenous estradiol reduces the concentrations of FSH [39], and an antiestrogen increases FSH concentrations and causes maturation of multiple follicles [40, 41].
Summary
Inhibin from the wave of growing follicles apparently is the principal, if not the only, systemic FSH suppressant during most of the common-growth phase in the three species. Circulating estradiol concentrations increase near the beginning of deviation, and it appears that both inhibin and estradiol contribute to the subsequent continuation of the FSH decline. The estradiol:deviation relationships in cattle and apparently in women are similar to those in mares, except for a longer interval in mares between increased estradiol secretion into the circulation and the beginning of deviation. A schematic diagram of the systemic relationships among FSH, total inhibin, estradiol, and follicle development is shown for mares (Fig. 8).
|
|
ROLE OF LH |
|---|
|
TOPABSTRACTINTRODUCTIONDEVIATION AND THE SIZE...FOLLICLE-STIMULATING...FOLLICULAR FSH SUPPRESSANTSROLE OF LHINTRAFOLLICULAR AND CELLULAR...REFERENCES |
|---|
In cattle, the granulosa cells had greater LH receptor (LHr) activity on the day after expected deviation than on the day before deviation [45, 46]. In a recent study [47], an increase in the differences between the two largest follicles in granulosa LHr mRNA expression occurred 8 h before an increase in the differences between the two follicles in diameter and in follicular-fluid estradiol concentration. The content of LHr protein in equine granulosa cells was greater when the follicles were 15–19 mm than 10–14 mm, and aromatase content was greater when the follicles were 20–24 mm than 15–19 mm [48]. In conclusion, the granulosa cells of the future dominant follicle acquire LHrs in heifers and apparently in mares just before the beginning of deviation, providing a pathway for a functional LH effect of the early portion of the transient LH elevation. Thus, the early portion of the LH elevation followed by the expression of LHr in the granulosa cells are the first known events that can be assigned to the cascade of events leading to deviation during the continuing FSH decline.
In cattle, an experimental reduction of LH by progesterone treatment at the expected beginning of deviation was associated with a reduction in the follicular-fluid concentrations of estradiol, androstenedione, and insulin-like growth factor (IGF)-1 in the two largest follicles (unpublished results). This result indicated that these factors are stimulated by the early portion of the LH elevation associated with deviation. Experimental reduction of LH concentrations decreased the diameter of the dominant follicle beginning 1 or 2 days after the beginning of deviation in cattle [43] and mares [49, 50]. The smaller diameter of the dominant follicle in association with experimental LH reduction also occurs in cattle in association with natural LH reduction. That is, lower concentrations of the LH elevation for wave 2 compared to wave 1 (discussed above) were associated with smaller diameter of the dominant follicle beginning 32 h after the beginning of deviation [43]. Reduction of LH by progesterone treatment beginning when the largest follicle was 9.0 mm (about 8 h after the beginning of deviation) resulted in a reduced diameter and concentrations of estradiol and IGF-1 in the follicular fluid of the dominant follicle 24 h later [43]. These results indicated that an LH requirement for normal postdeviation growth and function of the dominant follicle represents an influence of the postdeviation portion of the LH elevation. The role of the transient LH elevation is included in the schematic models (Figs. 8 and 9).
|
INTRAFOLLICULAR AND CELLULAR ASPECTS |
|---|
|
TOPABSTRACTINTRODUCTIONDEVIATION AND THE SIZE...FOLLICLE-STIMULATING...FOLLICULAR FSH SUPPRESSANTSROLE OF LHINTRAFOLLICULAR AND CELLULAR...REFERENCES |
|---|
|
Estradiol
In heifers, follicular-fluid estradiol concentrations began to increase in the largest follicle at the beginning of deviation [47, 55]. In mares, an increase in estradiol occurred in the follicular fluid [37], and echogenic changes characteristic of estrogen stimulation occurred in the wall [56] of the future dominant follicle the day before the beginning of deviation. In women, an increase in follicular-fluid estradiol occurred about the time the dominant follicle was first identifiable by its larger diameter [4, 12, 57]. Thus, for all three species, the beginning of increased local availability of estradiol approximately coincides with the beginning of deviation. Reported autocrine and paracrine activities of estradiol in the granulosa cells include enhancing aromatase enzyme activity, promoting expression of LHr, and enhancing the sensitivity to FSH and LH [58]; all of these functions seem relevant to the deviation mechanism. However, most of the studies on the role of estrogens in folliculogenesis were done in rodents. Specific study is needed in the monovular species because the local activities of estradiol may be crucial to the deviation mechanism. Increased responsiveness of the future or established dominant follicle to FSH could also occur through an increase in the number of FSH receptors in the granulosa cells; however, reported results in cattle on the differential acquisition of FSH receptors by the largest follicle versus the second-largest follicle seem inconclusive or inconsistent [46, 53, 54, 59].
The increased estradiol produced by the developing dominant follicle near the beginning of deviation may be attributed to the transient elevation in LH concentrations and the increased expression of LHr by the granulosa cells. The cellular model (Fig. 9) assumes that the increased LHr expression in the granulosa cells provides for direct LH-regulated activity of the cAMP system within the granulosa. In this regard, an LH-induced increase in cAMP and aromatase activity and estradiol synthesis occurred in cultured granulosa cells in humans [60]. In cattle, P450arom enzyme expression was higher in the granulosa of cells of follicles averaging 10.8 mm than in follicles averaging 7.8 mm [61]. However, direct LH-induced secretion of estradiol within the granulosa apparently has not been demonstrated in either cattle [51] or horses [62]. Further study is needed, using cells obtained near the time of deviation.
Insulin-Like Growth Factor System
The IGF system consists of IGF-1 and IGF-2, IGF receptors, and a family of binding proteins (IGFBPs) and IGFBP proteases [7]. The paracrine-autocrine activities of IGF-1 and -2 include increasing cell growth, increasing estradiol production, and enhancing the sensitivity of the granulosa cells to FSH in cattle [63, 64] and humans [13]. Theca cells possess IGF-1 receptors [65] and LH-stimulated synthesis of androgen by cultured theca cells is synergistically enhanced by the presence of IGF-1 [66]. Apparently, IGF-1 has the potential to exert positive paracrine action on the growth and steroidogenic function in both theca and granulosa cells [63, 67]. The role of the IGF system in deviation has been studied only in cattle. The levels of free IGF-1 did not change in the largest follicle while growing from 7.5 to 11.2 mm [47]. However, the concentrations of the free IGF-1 in the second-largest follicle decreased progressively during the same time span and was associated with continuously lower concentrations than in the largest follicle. These results suggested that the IGF system may be important to the deviation phenomenon. However, concentrations of free IGF-1 in the follicular fluid were not different between the two largest follicles when the largest follicle was a mean of 8.7 mm (near the beginning of expected deviation) [43]. In another study (unpublished results), the concentrations of free IGF-1 were not different between the two largest follicles at the expected time of deviation in 11 cattle. In the same study, estradiol concentrations were higher in the largest follicle, suggesting that changes in estradiol preceded changes in IGF-1. More study will be needed to clarify whether IGF-1 concentrations differ between the two largest follicles relative to the beginning of deviation and the increased production of estradiol.
Although there currently is ambiguity about the temporal relationship between IGF-1 concentrations and the beginning of deviation in cattle, results have consistently shown high concentrations of free IGF-1 in the postdeviation developing dominant follicle [43, 47]. Concentrations of free IGF-1 were higher in the dominant follicle when it was a mean of 10.8 mm than in the second largest follicle [43]. In this regard, granulosa cells of 9-mm follicles expressed mRNA for IGF-1 [68]. The postdeviation increase in IGF-1 apparently is important for optimal growth and function of the developing dominant follicle.
Experimental reduction of circulating LH concentrations was associated with lower levels of free IGF-1 in the follicular fluid of the two largest follicles near the expected beginning of deviation (largest follicle, 8.7 mm) and after deviation in cattle (largest follicle, 10.8 mm) (unpublished results), indicating another role for the transient elevation in LH. An LH-stimulated increase in estradiol production by the granulosa (discussed above) also could be secondary to the stimulation of the IGF system as suggested in cattle by the following: 1) the follicular-fluid concentrations of both IGF-1 and estradiol decreased when the circulating concentrations of LH were reduced near the time of deviation (unpublished results) and 2) the addition of IGF-1 to a granulosa culture system resulted in increased production of estradiol [69].
Insulin-like growth-factor binding proteins may play a role in deviation by decreasing the bioavailability of IGF-1 and thereby interfering with the growth of the subordinate follicles. The granulosa cells expressed mRNA for IGFBP-2, but thecal cells did not [70]. Concentrations of IGFBP-2 were similar between the largest and second-largest follicles at the expected beginning of deviation [47]. The differential changes in the concentrations of IGFBP-2 did not occur until the largest follicle had reached 9.5–10.5 mm; the levels were higher in the second-largest follicle. Experimental reduction of LH concentrations resulted in higher levels of IGFBP-2 in the two largest follicles, indicating an additional function of the transient LH elevation (unpublished results). In addition to synthesis in the follicles, the changes in IGFBPs and IGF-1 content of follicular fluid reflect an uptake from the blood.
Expression of IGFBP-4 mRNA by theca cells in cattle was similar for small (1–4-mm), medium (4–8-mm), and large (>8-mm) follicles; granulosa cells did not express IGFBP-4 mRNA [70]. In addition, LH stimulated the expression of IGFBP-4 by bovine theca cells in vitro. Nevertheless, the concentrations of IGFBP-4 were higher in the follicular fluid of the second- and third-largest follicles than in the largest follicle when it reached a mean of 7.6 mm [71]. Changes in IGFBP-4 levels in the follicular fluid have been attributed to IGFBP-4 specific protease in cattle [70] and humans [72]. The protease frees IGF-1 from the IGFBP-4:IGF-1 complex by degrading IGFBP-4. The protease was found in higher concentration in the largest follicle than in the second-largest follicle in heifers [73, 74]; however, the specimens were obtained after deviation, as indicated by mean estradiol concentrations in the largest follicle and second-largest follicle of 865 versus 5 ng/ml. An increase in IGFBP-4 protease and a decrease in IGFBP-4 reflect the availability of more IGFs to support the continued growth of the dominant follicle. In this regard, IGFBP-4 protease is regulated by IGF-1 in bovine and equine preovulatory follicles [75], and production of IGFBP-4 protease is stimulated by FSH in human granulosa cells [76]. At an unknown point relative to deviation, the largest follicle may have higher IGFBP-4 protease activity because of greater responsiveness of the largest follicle than the smaller follicles to low levels of FSH. The lower responsiveness of the smaller follicles to the declining levels of FSH would result in less IGFBP-4 proteolytic activity, increased IGFBP-4, and decreased IGF-1 in the follicular fluid.
Inhibin
An intrafollicular role for inhibin and other proteinaceous factors in deviation has not been demonstrated and is not included in the schematic model (Fig. 9). However, forms of activin and inhibin from the granulosa cells are involved in androgen production from the theca [77]. Activin stimulates cAMP, aromatase activity, estradiol production, and an increase in gonadotropin receptors. The production of inhibins (
and ßA-subunits) is stimulated by LH in vitro, apparently through the cAMP pathway [78]; however, LH stimulation of inhibin apparently has not been studied in vivo. In cattle, follicular-fluid concentrations of follistatin, inhibin-A, and various molecular-weight forms of inhibin were similar among the three largest follicles when the largest follicle was a mean of 7.6 mm [71]. In a study [47] using expected deviation as a reference, no differential change in total inhibin or inhibin-A was found between the largest follicle and the second-largest follicle before or at the beginning of deviation. In mares, inhibin , ßA, and ßB subunits were detected in granulosa cells of follicles >30 mm [33], but studies have not focused on deviation that is expected to occur at 22.5 mm.
In women, inhibin concentrations in the ovarian venous blood did not differ between the ovary with the dominant follicle and the opposite ovary [12]. However, during follicle growth, the follicular-fluid environment changes from higher levels of activin to higher levels of inhibin-A:follistatin [4]. Follicular-fluid inhibin-A, but not inhibin-B, concentrations increased in the two largest follicles as both diameter and maturity increased [4]. These workers concluded that a transition from an activin follicular environment to an inhibin-A:follistatin environment is critical for dominant follicle development; however, it is not known whether the change to an inhibin-A:follistatin environment is involved in the deviation mechanism or only in the maturation of the dominant follicle after deviation has been established.
Summary
The transient elevation in LH at deviation stimulates the IGF system, as well as the steroid system. At the beginning of deviation, the largest follicle is able to utilize the low concentrations of FSH, presumably enhanced by local effects of estradiol and IGF-1. The second-largest follicle has not developed to a similar extent and therefore cannot withstand the low FSH concentrations. Thereby, deviation is established before the second-largest follicle can develop to a stage that would allow it to assume the biochemical characteristics of a future dominant follicle.
|
ACKNOWLEDGMENTS |
|---|
|
FOOTNOTES |
|---|
1 Correspondence: O.J. Ginther, Department of Animal Health and Biomedical
Sciences, 1656 Linden Drive, University of Wisconsin-Madison,
Madison, WI 53706. FAX: 608 262 7420; ojg{at}ahabs.wisc.edu 
Accepted: March 19, 2001.
Received: October 13, 2000.
|
REFERENCES |
|---|
|
TOPABSTRACTINTRODUCTIONDEVIATION AND THE SIZE...FOLLICLE-STIMULATING...FOLLICULAR FSH SUPPRESSANTSROLE OF LHINTRAFOLLICULAR AND CELLULAR...REFERENCES |
|---|
, ßA, ßB subunits in the ovary. Biol Reprod 1998; 59:1392-1398-inhibin, and aromatase in relation to follicular growth, estrous cycle stage, and oocyte competence for in vitro maturation in the mare. Biol Reprod 1999; 60:1120-1127This article has been cited by other articles:
|
|
 |
|
  A. Sen, L. Lv, N. Bello, J. J. Ireland, and G. W. Smith Cocaine- and Amphetamine-Regulated Transcript Accelerates Termination of Follicle-Stimulating Hormone-Induced Extracellularly Regulated Kinase 1/2 and Akt Activation by Regulating the Expression and Degradation of Specific Mitogen-Activated Protein Kinase Phosphatases in Bovine Granulosa Cells Mol. Endocrinol., December 1, 2008; 22(12): 2655 - 2676. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 W.-Y. Son, J.-T. Chung, B. Herrero, N. Dean, E. Demirtas, H. Holzer, S. Elizur, R.-C. Chian, and S. L. Tan Selection of the optimal day for oocyte retrieval based on the diameter of the dominant follicle in hCG-primed in vitro maturation cycles Hum. Reprod., December 1, 2008; 23(12): 2680 - 2685. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J Buratini Jr., M.G.L Pinto, A.C Castilho, R.L Amorim, I.C Giometti, V.M Portela, E.S Nicola, and C.A Price Expression and Function of Fibroblast Growth Factor 10 and Its Receptor, Fibroblast Growth Factor Receptor 2B, in Bovine Follicles Biol Reprod, October 1, 2007; 77(4): 743 - 750. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Sen, A. Bettegowda, F. Jimenez-Krassel, J. J. Ireland, and G. W. Smith Cocaine- and Amphetamine-Regulated Transcript Regulation of Follicle-Stimulating Hormone Signal Transduction in Bovine Granulosa Cells Endocrinology, September 1, 2007; 148(9): 4400 - 4410. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Steckler, M. Manikkam, E. K. Inskeep, and V. Padmanabhan Developmental Programming: Follicular Persistence in Prenatal Testosterone-Treated Sheep Is Not Programmed by Androgenic Actions of Testosterone Endocrinology, July 1, 2007; 148(7): 3532 - 3540. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. J. Roberts, M. J. Al-Hassan, P. M. Fricke, and S. E. Echternkamp Large variation in steroid concentrations and insulin-like growth factor binding proteins exists among individual small antral follicles collected from within cows at random stages of the estrous cycle J Anim Sci, October 1, 2006; 84(10): 2714 - 2724. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Mihm, P.J. Baker, J.L.H. Ireland, G.W. Smith, P.M. Coussens, A.C.O. Evans, and J.J. Ireland Molecular Evidence That Growth of Dominant Follicles Involves a Reduction in Follicle-Stimulating Hormone Dependence and an Increase in Luteinizing Hormone Dependence in Cattle Biol Reprod, June 1, 2006; 74(6): 1051 - 1059. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. Moore and W. W. Thatcher Major advances associated with reproduction in dairy cattle. J Dairy Sci, April 1, 2006; 89(4): 1254 - 1266. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. C Jayawardana, T. Shimizu, H. Nishimoto, E. Kaneko, M. Tetsuka, and A. Miyamoto Hormonal regulation of expression of growth differentiation factor-9 receptor type I and II genes in the bovine ovarian follicle. Reproduction, March 1, 2006; 131(3): 545 - 553. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Shimizu, B. C Jayawardana, H. Nishimoto, E. Kaneko, M. Tetsuka, and A. Miyamoto Hormonal regulation and differential expression of neuropilin (NRP)-1 and NRP-2 genes in bovine granulosa cells. Reproduction, March 1, 2006; 131(3): 555 - 559. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Cao, J. Buratini Jr, J. G Lussier, P. D Carriere, and C. A Price Expression of protease nexin-1 and plasminogen activators during follicular growth and the periovulatory period in cattle Reproduction, January 1, 2006; 131(1): 125 - 137. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J Buratini Jr, A B Teixeira, I B Costa, V F Glapinski, M G L Pinto, I C Giometti, C M Barros, M Cao, E S Nicola, and C A Price Expression of fibroblast growth factor-8 and regulation of cognate receptors, fibroblast growth factor receptor-3c and -4, in bovine antral follicles Reproduction, September 1, 2005; 130(3): 343 - 350. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Ndiaye, T. Fayad, D. W. Silversides, J. Sirois, and J. G. Lussier Identification of Downregulated Messenger RNAs in Bovine Granulosa Cells of Dominant Follicles Following Stimulation with Human Chorionic Gonadotropin Biol Reprod, August 1, 2005; 73(2): 324 - 333. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Lopez, R. Sartori, and M. C. Wiltbank Reproductive Hormones and Follicular Growth During Development of One or Multiple Dominant Follicles in Cattle Biol Reprod, April 1, 2005; 72(4): 788 - 795. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. C. Woods and A.L. Johnson Regulation of Follicle-Stimulating Hormone-Receptor Messenger RNA in Hen Granulosa Cells Relative to Follicle Selection Biol Reprod, March 1, 2005; 72(3): 643 - 650. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E L Gastal, M O Gastal, M A Beg, and O J Ginther Interrelationships among follicles during the common-growth phase of a follicular wave and capacity of individual follicles for dominance in mares Reproduction, October 1, 2004; 128(4): 417 - 422. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T.J. Acosta, E.L. Gastal, M.O. Gastal, M.A. Beg, and O.J. Ginther Differential Blood Flow Changes Between the Future Dominant and Subordinate Follicles Precede Diameter Changes During Follicle Selection in Mares Biol Reprod, August 1, 2004; 71(2): 502 - 507. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
O.J. Ginther, E.L. Gastal, M.O. Gastal, and M.A. Beg Critical Role of Insulin-Like Growth Factor System in Follicle Selection and Dominance in Mares Biol Reprod, May 1, 2004; 70(5): 1374 - 1379. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
O.J. Ginther, E.L. Gastal, M.O. Gastal, C.M. Checura, and M.A. Beg Dose-Response Study of Intrafollicular Injection of Insulin-Like Growth Factor-I on Follicular Fluid Factors and Follicle Dominance in Mares Biol Reprod, April 1, 2004; 70(4): 1063 - 1069. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. E. Echternkamp, A. J. Roberts, D. D. Lunstra, T. Wise, and L. J. Spicer Ovarian follicular development in cattle selected for twin ovulations and births J Anim Sci, February 1, 2004; 82(2): 459 - 471. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Fayad, V. Levesque, J. Sirois, D. W. Silversides, and J. G. Lussier Gene Expression Profiling of Differentially Expressed Genes in Granulosa Cells of Bovine Dominant Follicles Using Suppression Subtractive Hybridization Biol Reprod, February 1, 2004; 70(2): 523 - 533. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J M Haughian, O J Ginther, K Kot, and M C Wiltbank Relationships between FSH patterns and follicular dynamics and the temporal associations among hormones in natural and GnRH-induced gonadotropin surges in heifers Reproduction, January 1, 2004; 127(1): 23 - 33. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
O.J. Ginther, D.R. Bergfelt, M.A. Beg, C. Meira, and K. Kot In Vivo Effects of an Intrafollicular Injection of Insulin-Like Growth Factor 1 on the Mechanism of Follicle Deviation in Heifers and Mares Biol Reprod, January 1, 2004; 70(1): 99 - 105. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. M. Quirk, R. G. Cowan, R. M. Harman, C.-L. Hu, and D. A. Porter Ovarian follicular growth and atresia: The relationship between cell proliferation and survival J Anim Sci, January 1, 2004; 82(13_suppl): E40 - 52. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Webb, P. C. Garnsworthy, J.-G. Gong, and D. G. Armstrong Control of follicular growth: Local interactions and nutritional influences J Anim Sci, January 1, 2004; 82(13_suppl): E63 - 74. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C.M. Perks, P.V. Newcomb, M. Grohmann, R.J. Wright, H.D. Mason, and J.M.P. Holly Prolactin acts as a potent survival factor against C2-ceramide-induced apoptosis in human granulosa cells Hum. Reprod., December 1, 2003; 18(12): 2672 - 2677. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. Sisco, L. J. Hagemann, A. N. Shelling, and P. L. Pfeffer Isolation of Genes Differentially Expressed in Dominant and Subordinate Bovine Follicles Endocrinology, September 1, 2003; 144(9): 3904 - 3913. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. J. Whale, D. C. Eckery, and J. L. Juengel Determination of Steroidogenic Potential of Ovarian Cells of the Brushtail Possum (Trichosurus vulpecula) Biol Reprod, September 1, 2003; 69(3): 947 - 958. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. M. Rivera and J. E. Fortune Proteolysis of Insulin-Like Growth Factor Binding Proteins -4 and -5 in Bovine Follicular Fluid: Implications for Ovarian Follicular Selection and Dominance Endocrinology, July 1, 2003; 144(7): 2977 - 2987. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. LeCouter, R. Lin, G. Frantz, Z. Zhang, K. Hillan, and N. Ferrara Mouse Endocrine Gland-Derived Vascular Endothelial Growth Factor: A Distinct Expression Pattern from Its Human Ortholog Suggests Different Roles as a Regulator of Organ-Specific Angiogenesis Endocrinology, June 1, 2003; 144(6): 2606 - 2616. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. M. Rivera and J. E. Fortune Selection of the Dominant Follicle and Insulin-Like Growth Factor (IGF)-Binding Proteins: Evidence that Pregnancy-Associated Plasma Protein A Contributes to Proteolysis of IGF-Binding Protein 5 in Bovine Follicular Fluid Endocrinology, February 1, 2003; 144(2): 437 - 446. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
O.J. Ginther, M.A. Beg, K. Kot, C. Meira, and D.R. Bergfelt Associated and Independent Comparisons Between the Two Largest Follicles Preceding Follicle Deviation in Cattle Biol Reprod, February 1, 2003; 68(2): 524 - 529. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
O.J. Ginther, C. Meira, M.A. Beg, and D.R. Bergfelt Follicle and Endocrine Dynamics During Experimental Follicle Deviation in Mares Biol Reprod, September 1, 2002; 67(3): 862 - 867. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
O.J. Ginther, M.A. Beg, D.R. Bergfelt, and K. Kot Activin A, Estradiol, and Free Insulin-Like Growth Factor I in Follicular Fluid Preceding the Experimental Assumption of Follicle Dominance in Cattle Biol Reprod, July 1, 2002; 67(1): 14 - 19. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
F.X. Donadeu and O.J. Ginther Changes in Concentrations of Follicular Fluid Factors During Follicle Selection in Mares Biol Reprod, April 1, 2002; 66(4): 1111 - 1118. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
10 mm in the new wave were established by sequential ablations as needed. Three groups with zero, one, or three retained follicles are shown for each hormone. Data were normalized to the day the largest follicle (LF) reached 13 mm. Three retained follicles were more effective than one retained follicle in increasing the inhibin concentrations and decreasing the FSH concentrations. This differential effect ceased at the expected beginning of diameter deviation or when the largest follicle was 23 mm. A star indicates a difference (P < 0.05) in hormone concentrations between the groups with one and three retained follicles. The significant difference occurred on the same day for the two hormones
