Gonadotropins and preantral follicular maturation in women

Ovarian follicular waves during the menstrual cycle: physiologic insights into novel approaches for ovarian stimulation

Elucidation of multiple waves of antral ovarian follicular development during the menstrual cycle has challenged traditional concepts of female reproductive physiology and foundations of assisted reproductive therapies. Approximately two-thirds of women develop two follicle waves throughout an interovulatory interval and the remainder exhibit three waves of follicle development. Major and minor waves of follicle development have been observed. Major waves are those in which a dominant follicle develops; dominant follicles either regress or ovulate. In minor waves, physiologic selection of a dominant follicle is not manifest. Knowledge of waves of antral follicular development has led to the global adoption of novel ovarian stimulation strategies in which stimulation can be initiated at various times throughout the cycle. Random-start and luteal-phase ovarian stimulation regimens have had important clinical applications for women requiring urgent oocyte or embryo cryopreservation for fertility preservation prior to chemotherapy. Ovarian stimulation twice in the same cycle, referred to as double stimulation, may be used to optimize clinical outcomes in women with a poor ovarian response to stimulation as well as in those requiring fertility preservation before chemotherapy.

Comparison of detection of normal puberty in girls by a hormonal sleep test and a gonadotropin-releasing hormone agonist test

CONTEXT

The magnitude of sleep-related gonadotropin rise required to activate pubertal feminization is not established.

OBJECTIVE

The objective of the study was to determine the normal relationship of pubertal hormone responses to sleep and to GnRH agonist (GnRHag) challenge across the female pubertal transition.

DESIGN/SETTING

This was a prospective study in a General Clinical Research Center.

PARTICIPANTS

Sixty-two healthy 6- to 13-year-old volunteer girls participated in the study.

INTERVENTIONS

Interventions included overnight blood sampling followed by GnRHag (leuprolide acetate) injection.

PRIMARY OUTCOME VARIABLES

The primary outcome variables included LH, FSH, and estradiol.

RESULTS

LH levels rose steadily during sleep and after GnRHag throughout the prepubertal years. The LH response to sleep and GnRHag correlated well across groups (eg, r = 0.807, peak vs 4 h post-GnRHag value); however, this correlation was less robust than in boys (r = 0.964, P < .01). Sleep peak LH of 1.3 U/L or greater had 85% sensitivity and 2.1 U/L or greater 96% specificity for detecting puberty (thelarche). The LH 1-hour post-GnRHag value of 3.2 U/L or greater had 95% sensitivity and 5.5 U/L or greater 96% specificity for detecting puberty. Girls entered puberty at lower LH levels than boys. FSH levels rose day and night during the prepubertal years to reach 1.0 U/L or greater during puberty but discriminated puberty poorly. Estradiol of 34 pg/mL or greater at 20-24 hours after GnRHag was 95% sensitive and 60 pg/mL or greater was 95% specific for puberty. Thirty-six percent of overweight early pubertal girls had meager hormonal evidence of puberty.

CONCLUSIONS

These data suggest that sleep-related pubertal hormone levels critical for puberty are normally reflected in the responses to GnRHag testing across the normal female pubertal transition. Inconsistencies between clinical and hormonal staging may arise from peripubertal cyclicity of neuroendocrine function and from excess adiposity.

The role of luteinizing hormone activity in controlled ovarian stimulation

The role of LH in the natural menstrual cycle is undisputed. The active participation of LH in both steroidogenesis and ovulation is well established, but its potential effect on oocyte maturation in the issue of assisted reproduction protocols remains a topic of debate. Although several studies have added to our understanding of the specific actions of androgens in human follicular development, some discrepancies persist regarding their role in oocyte atresia. Clinical situations, where LH is either decreased or absent (e.g. in women with hypogonadotrophic hypogonadism or LH-receptor gene mutations), provide important data supporting the necessity for a minimal amount of LH to evoke ovulation. Recent use of GnRH antagonists, which results in profound suppression of LH concentration, in combination with the pharmacological production of recombinant gonadotrophins, has attracted the attention of investigators. Identification of sub-fertilized women, in whom LH administration could be beneficial and should be indicated, is arousing ever more interest. Based on the available data in the literature, the aims of this review are to assess the role of both endogenous and exogenous LH activity in stimulated cycles, and to evaluate the effects of recombinant human LH supplementation on the ovarian hormonal milieu and on the main outcomes of controlled stimulated cycles.

The role of luteinizing hormone in folliculogenesis and ovulation induction

OBJECTIVE

To review the physiologic, pathophysiologic, and clinical roles of LH in follicle and oocyte development and maturation and to assess the effects of LH content in exogenous gonadotropin preparations used for ovulation induction.

DESIGN

Critical review of the scientific literature devoted to folliculogenesis. Evaluation of comparison studies that used different gonadotropin preparations for ovulation induction.

CONCLUSION(S)

Folliculogenesis and oocyte maturation are complex processes that require the action of both LH and FSH. Luteinizing hormone is essential to provide the androgen substrate for estrogen synthesis, which in turn contributes to oocyte maturation and may play a relevant role in optimizing fertilization and embryo quality. Although the excessive LH secretion that is present in some disorders is detrimental to reproductive function, this is not applicable to ovulation induction with hMG because this menotropin does not increase daily plasma LH levels. The results of ovulation induction with hMG or FSH-only regimens did not differ in studies conducted in patients with polycystic ovary syndrome and in most studies conducted in ovulatory women undergoing assisted reproductive techniques; conversely, hMG was clearly superior to purified FSH for the treatment of hypogonadotropic hypogonadism. Miscarriage rates were not affected by the use of hMG. Thus, low but detectable LH concentrations positively influence the outcome of ovulation induction in patients with ovulatory disorders and women undergoing assisted reproductive techniques.

Etiology of anovulation in polycystic ovary syndrome

Various endocrine factors may contribute to the phenomenon of arrested follicular development, which is the hallmark of anovulatory infertility in polycystic ovary syndrome. Hypersecretion of luteinizing hormone and/or insulin, together with high intrafollicular concentrations of androgens, can interact to produce supraphysiological levels of cyclic AMP in granulosa cells, resulting in premature activation of terminal differentiation and, hence, arrest of follicle growth.

Thecal and interstitial cells in polycystic ovaries (PCO) in the rat

Two different types of experimentally-induced polycystic ovaries (PCO) have been examined. A macrocystic ovarian condition is induced by estradiol valerate (EV) injection, whereas a microcystic ovarian condition is engendered with subcutaneous estradiol implants. In both of these models thecal and secondary interstitial cells were characterized using three functionally significant indices. Expression of alkaline phosphatase was evaluated immunohistochemically, hCG/LH-binding capacity was assessed by means of EM radioautography, and the size and percent cytoplasmic area of intracytoplasmic lipid were determined, in the same cells, by morphometry. In both types of ovary, thecal cells of healthy and atretic follicles stained heavily for alkaline phosphatase whereas cystic theca exhibited little or no staining. Intermittent faintly stained patches of secondary interstitial cells, as well as intensely stained spheroidal cell clusters, were most numerous in the microcystic ovary and occurred less frequently in the macrocystic ovary. Cystic thecal cells in both conditions exhibited large lipid droplets and minimal hCG binding. Lipid droplet area was minimal and hCG binding maximal in secondary interstitial cells of both types of ovary. It is concluded that specific clusters of secondary interstitial cells are important steroidogenic elements in PCO, whereas cystic theca is relatively inert.

The diagnosis and management of intersex

The patient whose genitalia are ambiguous or are inappropriate for the assigned sex presents the physician with a set of problems requiring a thorough grasp of sexual differentiation, development and function. Although several reviews have covered various aspects of these matters, these texts do not cover recent advances in understanding normal and abnormal sexual development nor do they provide an integrated guide to the management of intersex cases. Our objectives are to show the clinical relevance of recent advances in understanding the determinants of normal and abnormal sexual differentiation, to indicate the improved diagnostic procedures now available and to provide specific guidelines for optimal case management in the light of current medical knowledge and psychological and ethical understanding.

Morphogenetic reaggregation and luteinization of mouse preantral follicle cells

Small (60-90 micrometer) and large (100-130 micrometer) preantral follicles were isolated from adult mouse ovaries by a collagenase-dissection technique. These follicles were composed of resting oocytes surrounded either by granulosa cells, only, or by granulosa and undifferentiated theca cells. Further enzymatic dissociation of primary follicles yielded monodisperse cells characterized by abundant rough endoplasmic reticulum, microfilament-rich pseudopodia and only scant lipid droplets. These cells reaggregated, when explanted in stationary culture, forming epithelial cords and structures macroscopically reminiscent of native ovarian follicles. Anticipated association of follicular cells in epithelial-like monolayers was rare (less than or equal to 10% of all cultured cells). Formation and growth of both follicle-like (FLS) and cord-like (CLS) structures occurred within 24 hours of culture, continued for 14 days, and was inhibited by cytochalasin B, but not by neuraminidase. FLS and CLS, as well as cell monolayers, underwent luteinization, as indicated by the presence in the culture medium of radioimmunoassayable progesterone and by frequent cytological features suggestive of active steroidogenesis. The present report indicates that (a) specific cell affinities exist among immature follicular cells which may play a role in folliculogenesis; and (b) follicular cells are endowed, from their early developmental stages with intrinsic steroidogenic capabilities which become phenotypically expressed after escape from the intraovarian environment.

Hormonal correlates of normal and abnormal follicle growth after puberty in humans and other primates

After the menarche, changing levels of gonadotrophins, prolactin and sex steroid hormones in peripheral blood are accompanied by ovulation and corpus luteum formation in one follicle, and atresia in the remaining follicles maturing during each menstrual cycle. Available evidence suggests that blood levels of steroid hormones reflect in large part the secretory activity of the ovary containing a pre-ovulatory follicle and most probably of that follicle itself (see Chapter 6). These steroid secretions and those of the corpus luteum coordinate hypothalamic-pituitary-ovarian function. Within the ovary, sex steroid hormones mediate effects of gonadotrophins and prolactin on follicle maturation and participate in determining the fate of individual follicles.

Follicular growth in fetal and prepubertal ovaries of humans and other primates

Follicular growth begins in the fetal ovary as soon as the first follicles are formed. Although orderly follicular growth is found in the fetal ovary, many of the early growing follicles show abnormalties. Follicles with irregular granulosa layers, with hypertrophied or with underdeveloped theca layers, are characteristic. Such follicles are rarely seen after birth. The ovary during childhood is an active organ in which follicular growth and follicular atresia normally take place. Follicles begin to grow at all ages, differentiate to preantral and antral follicles, but degenerate at various stages of their development before they reach pre-ovulatory sizes. Follicular growth in the fetus and children is dependent on hormones. Fetal gonadotrophins are necessary to ensure normal and sequential follicular growth before birth. During childhood a close correlation between follicle growth, hormone response and hormone production seems to exist. Certain diseases and treatment with cytotoxic agents or radiation to the abdomen influence ovarian development and follicular growth. Chromosome abnormalities, especially Turner's syndrome, trisomy 18 or 21, alter normal ovarian development by reducing the pool of available follicles and inhibiting follicular growth. Treatment with cytotoxic drugs inhibits follicular growth, while abdominal irradiation in childhood unless the ovaries are adequately shielded causes permanent damage by destroying the small follicles.

Laparoscopic ovarian biopsy in seventy-one amenorrhoeic patients

During laparoscopy we performed 132 ovarian punch biopsies in seventy one amenorrhoeic patients. With increasing experience, laparoscopic ovarian biopsy is a valuable element in the examination of amenorrhoeic patients. Biopsy specimens with an edge length of 4-5 mm for surface and depth can be obtained during laparoscopy under general anaesthesia without any great risk or difficulty. When performed bilaterally, it provides a representative picture of the cellular structure and function of the ovaries and thus makes a contribution to the prognosis of a disturbance in the endocrine regulating-circuit of ovarian function. In addition, the ovarian biopsy provides information about the basic gonadotrophic situation of the patient as a longitudinal section. It should be included in the synopsis of all endocrine and genetic parameters of a patient, particularly in clinic in which the morphological substrate of disturbed functions and apparent diseases is still examined.

Hormonal changes of adolescence

Pubescence is characterized by many physical, emotional, and hormonal changes. The hypothalamic-pituitary-gonadal system is maintained in a dormant state (with a low level of activity) during prepubertal years by higher central nervous system inhibition. With the onset of adolescence, the reproductive endocrine system becomes increasingly active. The attainment of sexual maturity in terms of secondary sexual characteristics, the production of spermatozoa in the male, and the cyclical female pattern with release of ova are end-points of the developmental process.

The representability of laparoscopic ovarian biopsies for the cellular structure and function of the ovaries

Model biopsy specimens from 100 surgically removed ovaries were studied. They were matched in respect of size, dimensions and examination technique to 110 ovarian biopsy specimens obtained during laparoscopy from 60 amenorrhoeic patients. It was found that ovarian biopsy specimens with an all-round edge length of 4 to 5 mm permit usable conclusions in respect of the structure and hence also of the function of normal ovaries.

Monthly gonadotropin cycles in premenarcheal girls

Patterns of nocturnal excretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were investigated in 11 girls. Autoregressive digital filtering of low- and high-frequency variations was used to make patterns more apparent. Coincident FSH and LH surges, separated by an interval of 20 to 40 days, were seen in specimens from three of six postmenarcheal girls and three to five premenarcheal girls. This suggests that cyclic hypothalamic-pituitary-ovarian interactions occur before menarche.