Ovary and puberty

During puberty, the ovary is the endocrine and reproductive organ that translates central reactivation of the hypothalamic-pituitary-gonadal axis into follicular maturation, estradiol secretion, development of secondary sexual characteristics, acquisition of menstrual cyclicity and progressive ovulatory capacity. This is not a simple sudden “switching on” of ovarian function, but a long and gradual biological transition in which the pre-existing follicular reserve is progressively recruited in a setting of increasing GnRH pulsatility, rising FSH and LH levels, maturation of follicular steroidogenesis and peripheral changes involving the breast, uterus, bone, metabolism and central nervous system.

From a clinical perspective, female puberty is the point at which developmental physiology and endocrine pathology meet. Some girls show normal pubertal progression with considerable variation in timing, whereas others develop precocious puberty, delayed puberty, prolonged anovulation, primary amenorrhea or signs of ovarian insufficiency. These conditions are accompanied by issues specific to adolescence, such as the difficulty of distinguishing physiological postmenarchal menstrual irregularity from persistent ovarian dysfunction, the role of gonadal dysgenesis, the impact of chronic diseases and the need for pubertal induction programs in hypogonadal conditions. For this reason, medicine of the pubertal ovary requires age-specific criteria, longitudinal interpretation of clinical signs and constant integration of auxology, endocrinology and adolescent gynecology.

Pubertal ovarian function develops against a biological background that begins long before adolescence. The fetal ovary establishes the follicular pool during intrauterine life, and at birth a girl already possesses nearly her entire reserve of primordial follicles. After birth, there is a transient phase of neuroendocrine activation, often called mini-puberty, during which the hypothalamic-pituitary-gonadal axis shows temporary activity with secretion of gonadotropins and sex steroids. This phase does not produce true clinical puberty, but it demonstrates that the axis is biologically functional and allows an initial conditioning of ovarian, uterine and breast maturation. It is followed by a long period of relative quiescence during childhood, in which pulsatile GnRH activity is strongly inhibited.

The true pubertal transition begins when the central circuits controlling GnRH progressively reduce the inhibitory tone of childhood and increase pulsatile secretion, initially mainly during the night. Neurons expressing kisspeptin, neurokinin B and dynorphin play an important role in this process and are responsible for fine regulation of hypothalamic pulsatility. The gonadotropin that shows the earliest dynamic changes is LH, whose nocturnal secretion increases in the initial stages of puberty; subsequently, FSH also contributes more consistently to follicular growth. The ovary responds to these signals by recruiting antral follicles that are more sensitive to gonadotropin stimulation and by increasing estradiol production, which becomes the principal peripheral mediator of pubertal progression.

Clinically, the first visible sign of female puberty is generally thelarche, which reflects exposure of target tissues to increasing levels of ovarian estrogens. The appearance of the breast bud does not yet coincide with ovulatory maturity, but indicates that the ovary has begun to produce biologically significant amounts of estradiol. Subsequent stages include an increase in uterine volume, modification of the uterine body-to-cervix ratio, ovarian growth, an increase in the number and size of antral follicles, acceleration of linear growth and, later, the onset of menarche. Menarche does not represent the beginning of ovarian function, but rather a relatively late stage of a process that has already been underway for some time.

One of the most important concepts is that pubertal maturation of the ovary is not synchronous with the immediate acquisition of regularly ovulatory cycles. During the first years after menarche, many cycles are frequently anovulatory or have a suboptimal luteal phase, because coordination among the LH surge, final follicular maturation and luteal function requires further neuroendocrine maturation. This explains why menstrual irregularity, variation in cycle length and bleeding that is not entirely predictable are common during adolescence, without this automatically implying ovarian disease. However, persistent marked irregularity beyond the physiological window should prompt consideration of pathological causes.

Female puberty is also a critical window for other systems. Estradiol modulates growth velocity, contributes to the acquisition of bone mass, influences body composition, participates in endometrial maturation and acts on the brain in relation to behavior, sleep, emotional regulation and psychosexual development. The pubertal ovary should therefore not be interpreted as an isolated organ, but as an effector node within a network involving the hypothalamus, pituitary gland, adrenal gland, thyroid, insulin metabolism, bone and central nervous system. For this reason, even mild alterations in the timing or quality of ovarian function may have clinically relevant consequences for growth, bone health and psychological well-being.

In summary, the biology of the pubertal ovary is based on three progressive steps: central reactivation of the axis, ovarian follicular response with estrogen production and gradual acquisition of menstrual and ovulatory cyclicity. Understanding this sequence is essential for distinguishing physiological variability from true pubertal disorders and for correctly interpreting hormone tests and imaging during development.

The age at onset of female puberty shows significant physiological variability, but it nevertheless follows well-defined reference ranges. In most populations, thelarche occurs between 8 and 13 years of age, whereas menarche occurs on average approximately 2 to 3 years after the beginning of breast development. The rate of progression, however, is not uniform: some girls move through the stages of puberty rapidly, whereas others progress more slowly, and this heterogeneity reflects the interaction among genetic factors, nutritional status, the intrauterine environment, exposure to endocrine disruptors, ethnicity, chronic conditions and metabolic status. In practice, the epidemiology of puberty cannot be understood as a simple chronology, but rather as a distribution of developmental trajectories.

The genetic component is highly relevant. The timing of menarche and the age at pubertal onset show strong familial aggregation, and numerous genes involved in GnRH circuits, kisspeptin signaling, leptin signaling, gonadal development and steroidogenesis contribute to defining each individual pubertal window. In some girls, genetic predisposition results in familial early puberty or, conversely, constitutional delay; in others, true pathological conditions emerge, such as gonadal dysgenesis, defects of the GnRH receptor or primary ovarian insufficiency of chromosomal or monogenic origin. Genetic background therefore influences both normal physiology and the pathological vulnerability of the pubertal ovary.

Nutritional status and energy metabolism play an equally important role. Puberty requires the body to perceive sufficient energy availability, and signals such as leptin and insulin indirectly contribute to neuroendocrine permissiveness. Girls with obesity often show a tendency toward earlier thelarche and, in some cases, altered pubertal timing; however, earlier external signs do not always coincide with full and orderly activation of the gonadal axis. Conversely, malnutrition, excessive physical exercise, eating disorders and chronic systemic diseases may slow or arrest pubertal progression by reducing GnRH pulsatility and impairing ovarian function.

The fetal and childhood endocrine environment also leaves an imprint on pubertal maturation. Gestational age, birth weight, postnatal catch-up growth, exposure to tobacco smoke, endocrine disruptors and certain forms of early biological stress may influence the timing of puberty. The literature on substances such as BPA, phthalates and PFAS does not always provide consistent results, but confirms that the pubertal axis is sensitive to environmental exposures capable of interfering with steroid receptors, hormone metabolism and neuroendocrine signaling. Clinically, this does not mean mechanically attributing a direct causal effect to every exposure, but rather recognizing that female puberty is a biological process open to environmental influence.

A specific epidemiological issue concerns conditions that alter the follicular pool or the ability of the ovary to respond to gonadotropins. Turner syndrome and other chromosomal abnormalities are classic causes of insufficient pubertal development or incomplete progression. Gonadotoxic cancer therapies, ovarian surgery, autoimmune diseases, galactosemia, X-linked chromosomal fragility and idiopathic causes may also compromise ovarian function during puberty or shortly thereafter. These cases are not the most common in the general population, but they have major clinical relevance because they profoundly affect reproductive prognosis, bone health and the need for replacement therapy.

The epidemiological summary is that normal pubertal development depends on the convergence of genetics, energy availability, environment and the integrity of the ovarian reserve. For this reason, every clinical assessment of pubertal timing must be contextualized within family history, growth, BMI, chronic diseases, previous therapies and risk factors for primary ovarian impairment.

Ovarian puberty is the transition from a reserve of quiescent follicles to an endocrine function capable of supporting estrogenic development, growth of the internal genital tract and, progressively, ovulation. The follicle is the functional unit of the ovary: it contains the oocyte and consists of granulosa and theca cells, which progressively acquire distinct endocrine functions. Low-level follicular activity exists during childhood, but during puberty gonadotropin stimulation gives antral follicles the ability to produce increasing amounts of estradiol. FSH stimulates granulosa cell proliferation and aromatase activity, whereas LH acts mainly on theca cells by promoting androgen synthesis, after which these androgens are converted into estrogens within the follicle.

This two-cell, two-gonadotropin model is one of the cornerstones of pubertal ovarian physiology. The increase in estradiol is not an isolated event, but the result of increasingly effective cooperation between the theca and granulosa compartments. At the same time, the ovary also secretes inhibin B and AMH, markers that reflect different aspects of follicular activity. Inhibin B tends to correlate with FSH-dependent follicular function, whereas AMH is produced by small growing follicles and primarily represents an indicator of the recruitable follicular pool. During adolescence, these markers may provide useful information, but their interpretation must always be contextualized because they do not replace a comprehensive clinical assessment of pubertal development.

As estradiol levels rise, coordinated changes occur in target tissues. The breasts progress through successive Tanner stages, the uterus grows and changes its morphology, the endometrium acquires the capacity for cyclical proliferation and body fat distribution takes on a more typically female pattern. Bone also responds strongly to estrogen signaling: estradiol contributes to the pubertal growth spurt and, subsequently, to epiphyseal maturation. For this reason, altered ovarian function during this phase may have effects extending beyond reproduction and may influence final height and bone mineral density.

Menarche occurs when the axis has reached a sufficient degree of estrogenic and uterine maturation, but it does not coincide with full ovulatory maturity. During the first years after menarche, many cycles are anovulatory, and intermenstrual variability is physiologically greater than in adults. This occurs because the positive estrogen feedback mechanism required for the ovulatory LH surge and subsequent luteal function has not yet stabilized. Progressively, as GnRH pulsatility and pituitary and ovarian sensitivity become consolidated, the proportion of ovulatory cycles increases and cycle length tends to become more regular.

A very important point is distinguishing the physiology of adolescent anovulation from true ovarian disease. Moderate irregularity during the first gynecological years after menarche may be a normal expression of incomplete maturation of the axis. However, very widely spaced bleeding, prolonged amenorrhea, clinical hyperandrogenism, incomplete or absent pubertal progression, or persistently elevated gonadotropins indicate that the situation is no longer within the range of simple physiological variability. In such cases, the problem concerns not only timing, but also the quality of pubertal ovarian function.

In summary, ovarian puberty is the gradual development of endocrine and ovulatory follicular competence. Its clinical outcome is not merely the onset of menarche, but the acquisition of cyclical function capable of integrating follicular growth, estrogen production, central feedback and future fertility.

When signs of ovarian activation appear too early or too late, the primary clinical issue concerns pubertal timing. Central precocious puberty in girls corresponds to premature activation of the hypothalamic-pituitary-ovarian axis, with progressive breast development, increased growth velocity, advanced bone age and ultrasound changes in the uterus and ovaries. In this setting, the ovary is not the primary source of the disorder, but its peripheral effector: it receives a pubertal gonadotropin signal prematurely and responds with estrogen production and progression of secondary sexual characteristics. Distinguishing this condition from isolated premature thelarche is essential, because breast signs may be present in the latter without full, progressive pubertal activation.

The clinical relevance of precocious puberty depends not only on chronological advancement, but also on its biological consequences. Premature excessive estrogen exposure accelerates skeletal maturation and may reduce adult height through early closure of the growth plates. It also exposes the girl to a mismatch between bodily maturation and emotional and cognitive development, with psychological and social consequences. Not all forms require treatment, but rapid progression, a very early age at onset and the anticipated impact on height and psychosocial well-being make a structured specialist assessment necessary.

At the opposite extreme, delayed puberty in girls is classically defined as the absence of breast development by the expected age or failure to progress after an initial onset. In these cases, the problem may be upstream, with functional or organic hypogonadotropic hypogonadism, or downstream, with an inadequate ovarian response and a pattern of hypergonadotropic hypogonadism. The ovary assumes a central role because gonadal dysgenesis, primary ovarian insufficiency, Turner syndrome, gonadotoxic injury or genetic follicular dysfunction prevent adequate estradiol production and arrest pubertal progression. Presentation may range from complete absence of thelarche to partial initial development followed by arrest.

There are also forms of incomplete or disordered puberty, in which thelarche appears but does not progress appropriately, or menarche occurs without adequate subsequent regularization, or signs of estrogenization coexist with significant ovulatory dysfunction. These patterns require more refined reasoning because they may reflect simple immaturity of the axis during the first postmenarchal years, but they may also be associated with ovarian hyperandrogenism, evolving PCOS, partial hypogonadism, hyperprolactinemia, hypothalamic dysfunction caused by energy deficiency or systemic diseases. In practice, progression is as important as the age at onset.

A correct assessment of pubertal timing must always distinguish gonadarche from adrenarche. The appearance of pubic or axillary hair may result from adrenal activation and does not necessarily imply that the ovary is already fully active. Conversely, the most reliable sign of ovarian estrogenization remains progressive breast development associated with uterine growth and consistent hormonal changes. Confusing these processes may lead to overdiagnosis of precocious puberty or delayed puberty when only developmental variants are present.

The final clinical message is that pubertal timing cannot be assessed on the basis of a single visit, but requires the combination of chronological age, rate of progression, linear growth, bone age, hormone measurements and pelvic imaging. Only longitudinal evaluation can determine whether the ovary is following a physiological trajectory, an early but benign trajectory, or a truly pathological one.

The absence of menarche beyond the expected age or persistent marked menstrual irregularity after the onset of puberty shifts attention from simple pubertal chronology to the quality of ovarian function. Primary amenorrhea is a heterogeneous condition that may result from absent estrogenization, anatomical outflow defects, Müllerian anomalies or disorders of the hypothalamic-pituitary-ovarian axis. From an ovarian perspective, the most relevant patterns are those in which the ovary does not produce adequate amounts of estradiol or cannot sustain effective folliculogenesis. In these situations, thelarche may be absent, limited or incomplete, and the gonadotropin profile helps distinguish central causes from primary ovarian causes.

Adolescent anovulation requires separate consideration. During the first years after menarche, a high proportion of anovulatory cycles is physiological, but when irregularity persists and is associated with hyperandrogenism, very widely spaced bleeding or metabolic signs, a persistent disorder of ovarian function must be considered. The most common condition is adolescent PCOS, but diagnosis at this age must be cautious because acne, irregular cycles and multifollicular ovaries may also occur during the normal pubertal transition. International guidelines therefore recommend adolescent-specific criteria and advise against basing the diagnosis solely on ovarian ultrasound during the first postmenarchal years.

True primary ovarian insufficiency during adolescence is less common but far more important prognostically. In these cases, the ovary prematurely loses follicular or steroidogenic capacity, and the biochemical pattern typically shows elevated gonadotropins with low estradiol. Causes include gonadal dysgenesis, classic or mosaic Turner syndrome, injury following chemotherapy or radiotherapy, autoimmune causes, galactosemia, genetic mutations and idiopathic forms. Presentation may consist of complete absence of puberty, pubertal arrest, primary amenorrhea or early loss of menstrual function after an initial menarche.

The clinical importance of recognizing primary ovarian insufficiency is not limited to future fertility. Estrogen deficiency during adolescence impairs attainment of peak bone mass, uterine maturation, vasomotor and sexual well-being, and may have a major psychological impact. In addition, some etiologies require further evaluation for systemic comorbidities, as in gonadal dysgenesis with a risk of gonadal tumors or Turner syndrome with cardiovascular, renal and metabolic involvement. For this reason, diagnosis must be early and should never be deferred in favor of passive observation when puberty does not progress.

Another delicate issue is functional prognosis. Some girls with ovarian insufficiency have intermittent residual function, and the diagnosis does not always imply the immediate and irreversible total loss of all follicular activity. Nevertheless, the clinical priorities remain correcting hypoestrogenism, protecting bone and pubertal development, and providing realistic but not fatalistic counselling regarding fertility, sexuality, future reproductive options and the need for long-term follow-up.

In summary, primary amenorrhea and adolescent anovulation are symptoms, not diagnoses. The clinician's task is to determine whether these patterns reflect simple postmenarchal immaturity, functional ovarian dysfunction, persistent hyperandrogenism or true primary ovarian insufficiency, because the therapeutic and prognostic implications differ profoundly.

Assessment of the ovary during puberty should be structured as a sequential process integrating auxology, pubertal staging, laboratory testing and imaging. The first step is always clinical: age at onset of pubertal signs, rate of progression, family history of menarche and pubertal disorders, growth pattern, weight changes, intense sports activity, dietary restriction, headache, neurological symptoms, chronic diseases, gonadotoxic therapies and the presence of autoimmunity or dysmorphic features. Physical examination should include Tanner staging, height, BMI, growth velocity, any stigmata of Turner syndrome, signs of hyperandrogenism, galactorrhea and assessment of estrogenized mucosa when clinically appropriate.

The basic laboratory evaluation generally includes LH, FSH and estradiol, but their interpretation during puberty requires caution because values vary with maturational stage, sampling time and assay sensitivity. In suspected central precocious puberty, ultrasensitive basal LH, stimulation testing with GnRH or analogues and correlation with bone age may be useful. In delayed puberty or primary amenorrhea, prolactin, TSH and FT4 also become relevant and, according to the clinical suspicion, 17-hydroxyprogesterone, androgens, DHEAS and cortisol may be indicated. Elevated gonadotropins with low estradiol suggest primary ovarian insufficiency, whereas low or inappropriately normal levels suggest a hypothalamic-pituitary defect or functional suppression of the axis.

Pelvic ultrasound is very useful because it allows assessment of the presence and dimensions of the uterus and ovaries, ovarian volume, antral follicles, uterine morphology and indirect signs of estrogenization. In precocious puberty, increased uterine and ovarian volume and follicular growth support estrogenic activation; in delayed puberty, small uterine and ovarian dimensions suggest persistent hypoestrogenism. Ultrasound must nevertheless be interpreted cautiously: a multifollicular appearance is common in adolescence and cannot by itself establish a diagnosis of PCOS, whereas pelvic morphology must always be interpreted in relation to gynecological age and the hormonal profile.

Second-line investigations depend on the clinical context. In rapidly progressive or very early precocious puberty, brain magnetic resonance imaging may be indicated to exclude central causes. In primary amenorrhea with elevated gonadotropins, karyotyping, assessment for X chromosome abnormalities and, in selected cases, broader genetic testing should be considered. In suspected primary ovarian insufficiency, autoimmune investigations are useful and, in patients with a history of cancer treatment, gonadotoxic exposure should be reconstructed accurately. When the history and physical examination suggest Müllerian malformations or an outflow obstruction, the diagnostic pathway should include targeted gynecological imaging.

Follow-up is at least as important as the initial diagnosis. In precocious puberty managed without treatment, it is necessary to determine whether progression remains slow or becomes rapidly progressive. In girls with delayed puberty or incomplete development, serial reassessment of growth, Tanner stage, bone age, laboratory findings and psychological well-being helps distinguish conditions that are slowly maturing from those requiring treatment. In patients with primary or iatrogenic ovarian insufficiency, follow-up should include pubertal development, bone health, uterine maturation, adherence to therapy and long-term reproductive counselling.

In practice, diagnosis of the pubertal ovary does not arise from a single number, but from consistency among chronology, progression, hormonal data and pelvic morphology. Only this integration makes it possible to avoid both overmedicalization of physiological variability and delayed recognition of true pathological conditions.

Treatment of ovarian disorders during puberty depends on the pathophysiological mechanism and the clinical objective. In progressive central precocious puberty, the reference treatment consists of long-acting GnRH analogues, which suppress gonadotropin secretion and reduce ovarian estradiol production. The aim is not simply to halt pubertal signs, but to slow skeletal maturation, preserve adult height potential and reduce the mismatch between physical and emotional maturation. The therapeutic decision must nevertheless consider age at onset, rate of progression, bone age and psychosocial impact, because not all forms of early pubertal activation have the same clinical significance.

In delayed puberty caused by ovarian insufficiency or permanent hypogonadism, treatment has replacement and maturational purposes. Pubertal induction with estrogens should be gradual, using initially low doses followed by progressive increases to reproduce physiology as closely as possible. This approach promotes harmonious breast development, uterine growth, bone protection and a more physiological psychological adaptation. In girls with a uterus, once an adequate degree of estrogenization has been achieved and according to bleeding or endometrial development, a progestogen is added for endometrial protection and to establish replacement cycles.

Turner syndrome is the paradigm of induced puberty in the presence of primary ovarian insufficiency. Recent guidelines recommend planning estrogen introduction at an appropriate age, avoiding both excessive delay, which adversely affects bone, uterine development and psychological well-being, and overly rapid administration, which could compromise residual height potential. Treatment should be integrated with management of any growth impairment, cardiological monitoring and surveillance for the other comorbidities typical of the syndrome.

In adolescents with persistent anovulation or established PCOS, treatment depends on the predominant objectives: regulation of bleeding, control of hyperandrogenism, endometrial protection and metabolic management. Lifestyle changes play an important role when excess weight or insulin resistance is present, but they are not the only intervention. Combined estrogen-progestogen contraceptives, dermatological treatment and, in selected cases, metformin or other metabolic strategies may be indicated according to the clinical picture and guidelines. During adolescence, however, the priority is to avoid premature diagnoses and unnecessary chronic treatment in girls who are still within a physiological window of postmenarchal maturation.

A specific issue concerns patients at risk of gonadotoxic injury from cancer therapies. In these girls, management of puberty and ovarian function must be integrated with fertility preservation, assessment of residual ovarian reserve and planning of any replacement therapy. This requires dedicated centers and multidisciplinary counselling, because ovarian prognosis depends on age at treatment, the type of chemotherapy or radiotherapy and follicular status at the time of exposure.

In all pubertal conditions, therapeutic success also depends on adherence, communication and gradual progression. The girl and her family must understand the rationale for treatment, the expected timing of response, warning signs and the importance of follow-up. Treatment of the ovary during puberty is not merely a pharmacological prescription, but the construction of orderly and sustainable endocrine development over the long term.

The complications of pubertal ovarian disorders do not concern menstrual function alone, but also affect growth, bone, body image, mental health and future fertility. In untreated or rapidly progressive central precocious puberty, the principal biological consequence is excessive advancement of skeletal maturation with reduced adult height. This is accompanied by the psychological impact of a body maturing too early compared with peers, with a possible increase in distress, embarrassment, relational vulnerability and family stress. The problem is therefore not only endocrine, but also developmental and psychosocial.

In delayed puberty and primary ovarian insufficiency, the consequences occur on several levels. Estrogen deficiency impairs attainment of peak bone mass during a crucial phase of life, slows uterine maturation, may alter body composition and, if not corrected, may leave persistent effects on future skeletal and cardiovascular health. Psychologically, the absence of pubertal signs or their incomplete progression may impair self-esteem, self-image and social integration, particularly when comparison with peers is pronounced. Late diagnosis therefore increases both the biological and emotional burden.

In persistent adolescent anovulation and conditions compatible with PCOS, the risks concern chronic endometrial exposure to unopposed estrogens, persistent irregular bleeding, cutaneous hyperandrogenism with effects on acne, hirsutism and quality of life, and the possible association with insulin resistance and metabolic dysfunction. Follow-up is essential in these cases as well, because some adolescents develop a stable syndrome, whereas others improve with maturation of the axis or with targeted interventions involving weight and lifestyle.

Girls with primary ovarian insufficiency or gonadotoxic injury represent the group with the broadest long-term implications. In addition to requiring prolonged replacement therapy, they must address the issue of potentially reduced or uncertain fertility, with an impact on identity that may emerge as early as adolescence. In certain conditions, such as specific forms of gonadal dysgenesis, there is also a risk of gonadal tumors, which changes the surgical strategy, counselling and surveillance. Quality of life depends greatly on how this information is communicated: early but gradually, realistically but without catastrophizing.

A decisive step is the transition to adult care. Ovarian disorders beginning during puberty rarely end with adolescence. Years of monitoring are often required for hormone therapy, bone health, sexual function, fertility, metabolic risk and psychological support. An unstructured transition creates a risk of loss to follow-up, unsupervised discontinuation of treatment and the recurrence of avoidable complications. Therapeutic education should therefore begin during adolescence and aim to make the patient progressively autonomous in understanding her condition.

In summary, medicine of the pubertal ovary measures its success not only by the onset of menarche or normalization of LH, FSH and estradiol, but by broader functional outcomes: harmonious pubertal development, adequate bone mass, healthy psychological integration of bodily maturation, protection of endometrial health and the establishment of an informed long-term reproductive and care pathway.