Antral Fluid Research Articles

Size and shape changes in the preovulatory follicle in mares based on digital analysis of ultrasonic images

Computerized digital or pixel analysis of ultrasonic images was used to evaluate size and shape changes of preovulatory follicles in mares. Examinations of 12 preovulatory follicles were video-taped at 12-h intervals for 48 h and 1/2-h intervals for 3 h before ovulation. The maximum cross-sectional image of the antral area of each follicle was selected for each examination. A theoretical center was computed on basis of total pixel count for the antral area. Line lengths radiating from the center of the follicle to each pixel at the perimeter of the antrum were measured. For each examination of each follicle, size was represented by mean and median radial line lengths in pixels. Shape of each follicle was quantified by the magnitude of line length variance. There were no significant differences in the size of the preovulatory follicle during the 48 h prior to ovulation. Preovulatory follicle shape, as expressed by line length variance, differed significantly among examinations. The first significant shape change occurred between −12 and −3 h (mean line length variance, 32.3 and 66.1 pixels, respectively). An additional significant shape change was detected at −1/2 h (mean line length variance, 130.3 pixels). The increase in line length variance was attributed to a gradual flattening of the cross-sectional image of the antrum from circular to oblong as ovulation approached. The hypothesis that the equine preovulatory follicle loses its spherical shape as ovulation approaches was supported. Adjacent follicles (satellite follicles) that impinged on the preovulatory follicle were assessed for shape changes by subjective comparisons. The satellite follicles appeared to lose their flattened shape during the time that the cross-section of the preovulatory follicle was losing its circular shape. The shape changes in satellite and preovulatory follicles were attributed to a decline in antral fluid pressure from within the preovulatory follicle as ovulation approached.

Antroscopy in maxillary sinus disease associated with nasal polyposis

Although the association of maxillary sinusitis with nasal polyps is widely recognized little has been written on its precise incidence and degree. Antroscopy of 70 antra with ipsilateral polyps showed a high incidence of mucosal abnormalities, retained secretions and ostial narrowing. Comparison of these findings with preoperative X-rays showed the latter were unreliable in detecting retained antral fluid. It is concluded that in nasal polyposis the antra warrant careful assessment and that antroscopy is a highly satisfactory method for this purpose.

Human antral fluid IGF-I and oocyte maturity: effect of stimulation therapy

Studies in animals have highlighted a possible role for growth factors, particularly IGF-I on cellular replication and cytodifferentiation in the ovary. At this time, few studies have been performed about IGF-I in the human ovary. From 38 women undergoing in Vitro Fertilization 293 antral antral fluids were collected and assessed for steroids (estradiol and progesterone), FSH and IGF-I. Two induction treatments were compared: clomiphene citrate hMG (group A,N = 15), triptoreline/hMG (group B,N = 23). We also studied relationships between quantitative parameters and oocyte collection or oocyte corona cumulus complex maturity, In group B, the highest antral estradiol levels were found in follicles yielding an oocyte (p less than 0.05). Concerning antral progesterone, higher levels were observed in follicles collected from group A than follicles collected from group B (p less than 0.05): for this parameter, the highest levels were observed when an oocyte was harvested, whatever the treatment (p less than 0.05). Highest antral FSH levels were observed in group B (p less than 0.05). IGF-I levels were higher in follicles collected from group B than in follicles collected from group A (p less than 0.05) and antral IGF-I levels differed between mature and immature oocyte corona cumulus complex in group B (p less than 0.05). These results, which are in keeping with studies about biological action of IGF-I in animal or human follicles or granulosa cells, led us to hypothesize a role for IGF-I in human follicular recruitment and maturation, a role that possible is enhanced during GnRH analogue and gonadotropin therapy.

Interrelationships between plasma hormone levels and the content of total protein, gonadotropins and steroid hormones in antral fluids of women undergoing in vitro fertilization

Follicle development was induced in 41 women with follicle-stimulating hormone (FSH) and human menopausal gonadotropin. Blood samples were drawn and follicular fluids (FF) were aspirated when two or more follicles attained diameters of 15 to 17 mm. Levels of estradiol (E2), progesterone (P), FSH, and luteinizing hormone (LH) were determined in samples by radioimmunoassay, and relationships between the measured parameters in antral fluids and in serum were examined by least-squares linear regression analysis. Levels of LH in serum correlated with LH and FSH levels in FF (P less than 0.005). Concentrations of FSH in serum were positively related to levels of LH, FSH, E2, and total protein in FF (P less than 0.005). E2 levels in serum were predictive of E2 levels in FF only, and levels of P in serum were directly correlated with P levels in FF (P less than 0.05). With respect to the peculiarly broad range of predictions that could be drawn from the FSH content of serum, peripheral FSH provided a better predictive index of the chemical composition of antral fluid than did the level of any other single hormone measured in serum.

Electrophysiological properties of the follicle wall in the pig ovary.

The transmural potential difference and short-circuit current of the porcine Graafian follicle have been measured in an attempt to test whether antral fluid accumulates as a result of active transport of salt. The values obtained by mounting explants of follicle wall in Ussing chambers were close to zero and the specific electrical resistance was only 59 delta.cm2. The elemental composition of the follicular fluid was similar to that of ovarian venous plasma with the exception of follicular Na+ which was slightly more abundant. Bicarbonate concentrations were slightly lower in follicular fluids. These findings were interpreted as evidence that the follicular wall is a leaky epithelium and, therefore, any charge resulting from net ion transport will be shunted along low resistance paracellular pathways.

Levels of steroid and protein hormones in antral fluids of women treated with different combinations of gonadotropins, clomiphene citrate, and a gonadotropin-releasing hormone analog

Levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol, progesterone (P), and total protein in follicular fluids collected from 18 patients pretreated with a gonadotropin-releasing hormone analog (GnRHa), in association with human menopausal gonadotropin (hMG) and FSH, were compared with values for 69 patients treated with FSH, hMG, FSH/hMG, or clomiphene citrate (CC)/hMG in an in vitro fertilization (IVF) program. The authors have established a number of significant differences in chemical and physical properties of follicular fluids of patients treated by different regimen, and concur with earlier evidence that the volume of a follicle, and its P and total protein content, are related to the maturity of the oocyte nested within the follicle. Overall, however, differences in concentrations of gonadotropins in follicular fluids between groups were not consistent with differences in follicular fluid steroid levels, and levels of immunoactive gonadotropins in follicular fluids were not in accord with dosages of exogenous immunoactive gonadotropin administered during hyperstimulation. The most favorable outcomes of IVF (greater than 70% of oocytes fertilized) were established with oocytes collected from patients treated with FSH only or with CC/hMG, and patients treated with FSH only yielded the highest average number of oocytes which fertilized in vitro (6.2 per patient).

Intrafollicular paracrine function of ovarian androgen

During early antral stages of follicular development, granulosa cells are constantly exposed to a high local concentration of androgen. C 19 steroids biosynthesized in LH-stimulated theca cells traverse the lamina basalis, enter granulosa cells and accumulate in antral fluid. Within the granulosa cell layer, androgens are metabolized to other androgens, oestrogens and catechol oestrogens, all of which may fulfil intrafollicular regulatory functions. Observations in vitro show that direct androgen action in FSH-stimulated granulosa cells leads to increased generation of cyclic AMP with amplification of key cyclic AMP-dependent functions associated with granulosa cell differentiation. This could help explain why high concentrations of androgen in follicular fluid are associated with normal preovulatory follicular development and maintenance of oocyte viability in the mammalian ovary.

Synergistic actions of estradiol and the insulin-like growth factor somatomedin-C on swine ovarian (granulosa) cells.

Estradiol amplified synergistically the dose- and time-dependent stimulatory actions of human somatomedin-C on progesterone biosynthesis by cultured swine granulosa cells. This facilitative interaction was not attributable to inhibition of the catabolism of progesterone to 20 alpha-hydroxypregn-4-en-3-one, but, rather, reflected time-dependent stimulation of pregnenolone synthesis measured in the presence of exogenous soluble sterol substrate for cholesterol side-chain cleavage. Moreover, treatment with somatomedin-C was accompanied by increased synthesis of two immunoprecipitable cholesterol side-chain cleavage constituents, viz. cytochrome P-450scc and adrenodoxin. The synergism between estradiol and somatomedin-C was associated with significantly greater specific binding of somatomedin-C in estrogen-treated than control cultures, with no change in apparent receptor affinity. In vitro synergism occurred at somatomedin-C concentrations estimated by sequence-specific immunoassay to be attainable in ovarian follicular fluid in vivo and was specific in that it was not mimicked by the insulin-like peptide relaxin or by epidermal growth factor or fibroblast growth factor. However, high concentrations of insulin-like growth factor II (multiplication-stimulating activity) and insulin were able to interact with estradiol in a facilitative fashion to enhance progesterone production. In addition, the estrogenic component of the synergism was specific, since it was antagonized by the selective antiestrogen LY156758 and was mimicked sparingly by the nonaromatizable androgen 5 alpha-dihydrotestosterone. We conclude that estradiol and somatomedin-C interact synergistically in a time- and dose-dependent manner to enhance the biosynthesis of pregnenolone and progesterone by swine granulosa cells. Since estradiol and somatomedins are present in significant concentrations in the antral fluids of maturing Graafian follicles, we suggest that coordinated trophic effects of estradiol and insulin-like growth factor(s) may effectively prepare granulosa cells for the high rates of progesterone biosynthesis ultimately required after ovulation.

Bipotential Actions of Estrogen on Progesterone Biosynthesis by Ovarian Cells. I. Relation of Estradiol's Inhibitory Actions to Cholesterol and Progestin Metabolism in Cultured Swine Granulosa Cells*

In short term, serum-free cultures of granulosa cells, estradiol inhibited basal progesterone production by more than 84% in a time- and dose-dependent fashion. Half-maximal inhibition (ID50) was observed at a mean estradiol concentration of 70 ng/ml. The acute inhibitory effects of estradiol were independent of cell density or maturational status of the parent follicle (small, medium, or large follicles). Estrogen decreased total progesterone biosynthesis, rather than merely progesterone secretion by granulosa cells. In addition, the production of progesterone and its 20 alpha-reduced metabolite were suppressed in parallel over a 30-fold range of inhibitory effects. Moreover, estradiol inhibited progesterone production from both endogenous and exogenous (25-hydroxycholesterol) substrate. In contrast to its inhibition of progesterone production, estradiol acutely enhanced pregnenolone accumulation and led to a 14- to 20-fold increase in the ratio of pregnenolone to progesterone. Inhibition of 3 beta-hydroxysteroid dehydrogenase activity was confirmed by demonstrating estrogen's ability to antagonize the conversion of exogenously supplied pregnenolone to progesterone in intact granulosa cells (ID50, 74 ng/ml) and to directly inhibit enzymic activity in ovarian homogenates (ID50, 79 ng/ml). On the other hand, estradiol did not alter the incorporation of [14C]acetate into cholesterol and specific progestins or influence the time-dependent hydrolysis of prelabeled cholesteryl ester stores in granulosa cells. In summary, in short term cultures of swine granulosa cells, estradiol significantly inhibits basal progesterone biosynthesis in a time- and dose-dependent fashion, encompassing estradiol concentrations attainable in vivo. Estrogen's inhibition is accomplished by mechanisms that are independent of cytotoxicity, cell density, and maturational stage of the parent follicle. The predominant locus of estrogen action is blockade of pregnenolone's conversion to progesterone, rather than accelerated metabolism of progesterone to its 20 alpha-reduced metabolite. Moreover, estradiol simultaneously enhances functional cholesterol side-chain cleavage activity without suppressing de novo cholesterol biosynthesis or impairing the mobilization of cellular cholesteryl ester stores. Thus, we infer that increasing concentrations of estradiol attained in antral follicular fluid during the later stages of follicle maturation could effectively limit the premature secretion of large quantities of progesterone before ovulation without impairing the cell's capacity for de novo cholesterol biosynthesis or cholesteryl ester hydrolysis.

Role of estradiol as a biological amplifier of gonadotropin action in the ovary: in vitro studies using swine granulosa cells and homologous lipoproteins.

Swine granulosa cells cultured under serum-free conditions in vitro exhibit significant responsivity to the stimulatory actions of estradiol (E2) and FSH or LH. Under these conditions, granulosa cells harvested from either immature or mature Graafian follicles synthesized significantly increased quantities of progesterone in response to homologous low density lipoprotein (LDL) and, to a lesser degree, homologous high density lipoprotein (HDL) particles. The effects of LDL and HDL were dose dependent and saturable. The stimulatory influence of E2, FSH, or LH alone was significantly enhanced in the presence of pig LDL or HDL. Moreover, the synergism between E2 and FSH or between E2 and LH was significantly augmented by porcine LDL and, to a lesser degree, porcine HDL. To assess the physiological relevance of these observations, the lipoprotein contents of swine blood and follicular fluid were determined by heparin-manganese precipitation and after differential ultracentrifugation. The majority (greater than 70%) of cholesterol in pig blood resided in the LDL fraction, but follicular fluid was essentially devoid of LDL. On the other hand, follicular fluid contained large quantities of a presumptive HDL species with a density between 1.063-1.210. The HDL particle in follicular fluid was further characterized by agarose gel and sodium dodecyl sulfate-polyacrylamide gel electrophoreses, which demonstrated an alpha-migrating species whose major apoprotein exhibited an apparent mol wt of 28,000 and comigrated with human apoprotein A-1. Analytical ultracentrifugation of the pig follicular fluid HDL revealed a sedimentation coefficient (S20,w) of 4.93, similar to that of serum HDL (S20,w = 5.0). The physiological relevance of the HDL particle purified from follicular fluid was further demonstrated by its ability to significantly increase progesterone production by granulosa cells cultured under serum-free conditions in vitro. In summary, we have demonstrated striking responsivity of cultured pig granulosa cells to exogenously supplied LDL and, to a lesser degree, HDL, with further stimulation when cells are treated with estrogen and/or LH and FSH. Although LDL is the predominant lipoprotein in swine blood, it is essentially undetectable in the antral fluid of the intact Graafian follicle. Thus, the unambiguous in vitro responsiveness of granulosa cells to LDL that we observe suggests that the marked increase in availability of blood-borne LDL to granulosa-luteal cells that presumptively occurs at ovulation would contribute significantly to augmented rates of progesterone biosynthesis by luteal tissues in the pig.(ABSTRACT TRUNCATED AT 400 WORDS)

Factors regulating the growth of the preovulatory follicle in the sheep and human.

Around the time of luteal regression in monovular species a single dominant follicle, which will eventually ovulate, is selected from the population of antral follicles. The dominant follicle is characterized by its progressive increase in diameter due to increase in antral fluid volume as well as an increased number of granulosa cells. The crucial factor in the continued development of the dominant follicle is its ability to synthesize oestradiol under the influence of LH and FSH. In the sheep FSH secretion continues throughout the luteal phase while LH is suppressed. Thus development of large antral follicles continues so that when luteal regression occurs and LH secretion increases the final stages of development of the pre-antral follicle occur within 3 days. In the human, however, both FSH and LH are suppressed during the luteal phase and only rise when the levels of progesterone and oestradiol fall a few days before menstruation. This rise in FSH and LH which occurs at this time stimulates the further development of a small antral follicle (1-2 mm diameter). Within 7 days the favoured follicle establishes dominance over the other asynchronously developing follicles probably by inhibiting the secretion of FSH. As in the sheep, once aromatase enzyme(s) has been fully activated the dominant follicle is able to utilize the increased androgen precursor produced by the theca under LH stimulation.

Relationship among the status of the human oocyte, the 17 beta-estradiol concentration in the antral fluid and the follicular size.

We studied the relationship among the status of the human oocytes, the E2 concentration in the antral fluid and the follicular size in the different phases of the menstrual cycle, in order to determine the microenvironment of the follicles with healthy or degenerative oocytes in the human ovary. In the follicular phase of the menstrual cycle, follicles which contained a healthy but not degenerative oocyte had a significantly higher level of 17 beta-estradiol (E2). In the late follicular phase, the larger follicles (greater than or equal to 13 mm, in diameter) had only health oocytes. It seems that the follicle containing a degenerative oocyte does not develop physiologically until maturation of the preovulatory follicle. In the luteal phase, there were no relationships among the status of the oocyte, E2 concentration in the antral fluid and the follicular size. However, the E2 levels of the antral follicles with healthy oocytes in an ovary with corpus luteum were significantly lower than those in the contralateral ovary. The results suggest that the corpus luteum may exert an influence on the adjacent follicles.

Preovulatory follicular development in sheep treated with PMSG and/or prostaglandin.

Summary. The patterns of growth and atresia of antral follicles including that of the presumptive preovulatory follicle were examined in sheep ovaries for a 24–48-h period after the induction of luteolysis with a prostaglandin analogue, cloprostenol or cloprostenol + PMSG. Ewes were ovariectomized at various times after the initiation of the treatments. All follicles ≥1 mm in diameter were dissected from the excised ovaries and the antral fluid and granulosa cells recovered. Individual follicles were classified as healthy or atretic on the basis of the number of granulosa cells recovered and then subclassified as to whether they contained intrafollicular levels of oestradiol that were ≥ or < than 100 ng/ml. In another series of similarly treated ewes, the ovarian secretion rates of oestradiol and the intrafollicular concentrations of oestradiol in all large antral follicles (≥5 mm diameter) as well as the levels of progesterone in peripheral plasma were measured at different times after induction of luteolysis. The results showed that a large 'oestrogenic' follicle (≥5 mm diameter and secreting ≥1 ng oestradiol/min) appears around 10 h after the cloprostenol injection and that this presumptive preovulatory follicle emerges before the corpus luteum has ceased to function. Moreover, the presumptive preovulatory ('oestrogenic') follicle appears to develop from the pool of small 'oestrogenic' follicles (1–3 mm diameter) after the onset of luteolysis. The emergence of a large 'oestrogenic' follicle is accompanied by a widespread increase in atresia (> 80%) in all other classes of antral follicles (≥1 mm in diameter). During the first 10 h of cloprostenol-induced luteolysis, PMSG (a) prevented the normal occurrence of atresia in the large follicle population; (b) enhanced oestrogen secretion in a greater proportion of large antral follicles compared to that in control animals; (c) temporarily 'rescued' and/or prevented small antral follicles (1–4 mm diameter) from undergoing atresia; but (d) had little, or no, effect on the overall population of antral follicles (≥1 mm diameter). After 24 h, the atresia-preventing effects of PMSG were no longer discernible and the only obvious difference noted, compared to the controls, was the number of large oestrogen-secreting follicles.

Identification of the ovulatory follicle in the ewe: associated changes in follicular size, thecal and granulosa cell luteinizing hormone receptors, antral fluid steroids, and circulating hormones during the preovulatory period.

The presence of LH receptors in both thecal and granulosa cells appears to be required in preovulatory follicles. Since Finn and Suffolk sheep have significantly different ovulation rates, the number of Graafian follicles with LH receptors in both cell types was investigated to determine the relationship between the number of corpora lutea (CL) per ewe and the number of follicles with LH receptors in both cell types. Follicles with this characteristic LH binding were classified as ovulatory. All other follicles were considered to be nonovulatory. Follicular size, LH/hCG receptor concentrations in thecal and granulose cells, and antral fluid (AF) steroid concentrations were studied in ovulatory and nonovulatory follicles at two periods of the follicular phase of the estrous cycle in Finn and Suffolk sheep. Sheep were studied either before preovulatory gonadotropin surge or during the ascending limb of the preovulatory gonadotropin surge. The mean ovulation rate (2.7 CL per Finn ewe and 1.3 CL per Suffolk e...

Steroid and adenosine 3',5'-monophosphate formation in granulosa and thecal cells from human preovulatory follicles in response to human chorionic gonadotropin.

Granulosa and thecal cells from the preovulatory follicles of 14 women were mechanically isolated and separately incubated for short term periods (0.5-4 h) in the presence and absence of hCG. After incubation, tissue cAMP levels and medium progesterone content of (P), androstenedione (A), and 17 beta-estradiol (E2) were determined. All follicles appeared healthy and mature, as judged by their number of granulosa cells, histological examination of the oocytes, athe steroid levels in antral fluid, as well as the appearance of the oocyte-cumulus complexes. Under basal conditions, both granulosa and thecal cells had the capacity to synthesize all of the steroids measured. The predominant steroid formed by the granulosa cells was P, while the thecal cells formed A as the major steroid. Both cell types produced considerable amounts of E2. The addition of hCG in various concentrations gave rise to concentration-dependent increase in cAMP formation in both cell types. Furthermore, hCG caused a statistically significant increase in the formation of P and A by the thecal cells, while steroid formation by the granulosa cells was not significantly altered. With higher concentrations of hCG, however, there was a tendency toward a stimulation of P synthesis in the granulosa cells from most of the follicles tested. It is concluded that in preovulatory follicles of human origin, follicular steroidogenesis is not rigidly compartmentalized between the two cell types. Furthermore, both granulosa and thecal cells are sensitive to stimulation with hCG in this type of follicle.

Ovarian epithelial cancer and chemical carcinogenesis

Ovarian cancer is the most common fatal gynecological malignancy and is on the increase in industrialized countries. At this moment it is almost impossible to identify the high-risk patient. This cancer could be initiated by a chemical carcinogen via the vagina, uterus, and tubes and the substance promoting the cancer could be steroid-rich antral fluid from ruptured follicles. There is ample clinical evidence available for migration of chemical substances from the vagina to the peritoneal cavity and ovaries. By use of the radionuclide 99mTc-HAM upward migration was also demonstrated. Many different chemical substances are regularly used in the vulvo-vaginal areas and some of these could be implicated in carcinogenesis.

Follicular steroidogenesis and gonadotropin binding to ovine follicles during the estrous cycle.

The interrelationships among [125I]hCG binding in thecal and granulosa cells, antral fluid steroid concentrations, follicular size, and ovarian steroid secretion were examined at three different stages of the estrous cycle. Group 1 ewes were ovariectomized during the luteal phase of the estrous cycle, and the other groups were ovariectomized before (group 2), or after (group 3) the peak of the preovulatory LH surge. Times of luteolysis and the LH surge were assessed by measurement of peripheral concentrations of progesterone and LH. Three patterns of [125I]hCG binding to follicles were noted: 1) binding to both thecal and granulosa cells (activated follicle), 2) binding to the thecal cell layer only, and 3) no observed binding. In general, there was one active follicle per ewe, or one per ovary, and the number of active follicles was not different from the number of corpora lutea in each of the three groups. The active follicles were significantly larger than the other two classes of follicles. Antral fluid estradiol concentrations were significantly greater in the active follicles and were higher in group 2 ewes than in the other two groups. In group 2, antral fluid testosterone concentrations were significantly higher in follicles with LH receptors in the thecal cell layer only. Ovarian secretion of testosterone and estradiol increased during the early follicular phase (group 2), with the major secretion coming from the ovary containing the active follicle. Ovarian progesterone secretion was high in ovaries containing active corpora lutea which prevented the assessment of ovarian follicular secretion of progesterone. The follicle with LH receptors in thecal and granulosa cells was responsible for the increased estradiol secretion observed during the preovulatory period and is presumed to be the ovulatory follicle.

Relationship between follicular size and antral fluid steroid concentrations at three stages of the estrous cycle in the ewe.

Relationship between follicular size and antral fluid steroid concentrations at three stages of the estrous cycle in the ewe.

Changes in the Concentration of Gonadotrophic and Steroidal Hormones in the Antral Fluid of Ovarian Follicles Throughout the Oestrous Cycle of the Sheep

The concentrations of follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin, progesterone, androstenedione and oestradiol were determined in the antral fluid of ovarian follicles &gt; 1 mm in diameter as well as in ovarian venous or peripheral venous plasma, or both, from at least four different animals on each day throughout the oestrous cycle of the sheep. The individual steroid hormones in antral fluid were examined in relation to the steroid-secretion rates in ovarian venous plasma, follicle size and the hormone levels in jugular venous plasma.

Steroidogenesis by the human oocyte-cumulus cell complex in vitro

The ability of the human oocyte-cumulus cell complex to synthesize progesterone, androgens and estrogens and to modify its endocrine environment in vitro was investigated. Germinal-vesicle stage oocytes with adhering layers of cumulus cells were recovered from human ovaries and maintained for 40–50 h in vitro in a culture medium with or without antral fluid. The results show that oocyte-cumulus (0-C) cell complexes were capable of synthesizing progesterone, androgens and estrogens. Oocytes with the capacity of resuming meiosis in vitro were part of an 0-C complex producing significantly more progesterone than those 0-C complexes containing oocytes incapable of resuming meiosis. Irrespective of the stage of oocyte maturation at the end of culture, testosterone and estrone were respectively the major androgen and estrogen produced. It is concluded that the oocyte-cumulus compartment of the antral follicle is a steroidogenically competent unit and that it has the capacity to modify the endocrine microenvironment of the follicle.