Sexually Transmitted Diseases - I. I. Mavrov 2005

Puberty

Sex characteristics—morphological and functional traits that determine a person's biological sex—are divided into Primary and secondary. Primary characteristics include those that determine The Structure of the reproductive Organs, whereas secondary characteristics involve the structure and/or Functions of other non-reproductive organs (such as breast size, Hair distribution pattern, timbre of the voice, etc.). Sometimes tertiary sex characteristics are also distinguished, which are identified using special investigative Methods (the STRUCTURE OF THE pelvis and Skull, body Temperature, Blood composition, etc.).

In both sexes, the onset time and developmental dynamics of secondary sex characteristics vary widely (individual variations are often noticeable as early as early childhood) and depend on numerous endogenous and exogenous factors, such as previous stress, Nutrition, and environmental conditions.

At birth, the external and internal genitalia (primary sex characteristics) are already differentiated, although The Development of these organs, like that of the Organism as a whole, is not yet complete.

During the period from birth to the end of the 7th year of life (the parapubertal period), the development of boys and girls proceeds almost in parallel, with no deepening of sexual differences. This is the first, neutral phase of development, during which gender identity emerges and becomes established—a stable and irreversible self-identification as female or male (Table 1).

During the sexually differential period of development—the prepubertal period (ages 7–13)—boys and girls experience growth at different times ("stretching and broadening"), develop a female or male behavioral stereotype, and crystallize feminine or masculine character traits.

Puberty typically begins with a growth spurt. This process, along with adrenarche (the development of secondary pubic and body hair) and thelarche (breast development), is observed on average at 11 years of age. In most girls, menarche (the onset of menstruation) occurs at 12–13 years of age. In young males, the intensive puberty process generally starts at 10–11 years and lasts on average 4–6 years.

The puberty process is usually divided into periods, the number and age limits of which vary among different authors (Tables 1–5).

During the parapubertal period (ages 1–7), secondary sex characteristics are not yet developed in boys. The Testes are more spherical than elongated, measuring approximately 1–1.5 cm in diameter. The Scrotum lacks folds and pigmentation. The length of the Penis is 2–3 cm, and hyperemia is absent.

The prepubertal period (ages 7–11) is sometimes divided into two sub-periods: peripubertal and neopubertal.

Class="center">Table 1 Formation and dynamics of sexuality (according to V. M. Maslov, I. L. Botneva, G. S. Vasylchenko, 1983)

Table 2 Classification of puberty stages in boys (according to J. M. Tanner, 1962)

Note. * - differentiation of stages III–IV may be difficult.

Table 3 Classification of puberty stages in girls (according to J. M. Tanner, 1962)

Table 4 Sequence of appearance of puberty signs and their average age indicators (according to H. Seckel, 1946)

Table 5 Main parameters of age-related manifestations of sexuality (according to G. S. Vasylchenko, 1977)

To date, there is sufficient evidence that, starting from the INTRAUTERINE DEVELOPMENT OF the Pituitary Gland, the gonads exhibit an individual, active rhythm of functioning. Once a certain threshold of hormonal activity is reached, functional connections are established between them. Throughout ontogenesis, these connections are refined and complicated, ultimately forming a unified functional hypothalamic-pituitary-gonadal system by the time of puberty.

The physiological mechanisms of sexual development depend on increased hypothalamic secretion of factors (releasing Hormones) that stimulate the release of gonadotropic Pituitary Hormones. For the activation of the hypothalamic-pituitary-gonadal system to occur, a certain critical level of Central Nervous system (CNS) maturity is presumably required. This is partly related to the increased sensitivity of gonadotropic Cells to releasing hormones. It is hypothesized that humans experience several periods of hypothalamic-pituitary-gonadal system activation.

The first period is the time of embryonic development when the sex of the embryo is differentiated; the second is early childhood; and the third is adolescence. During puberty, neurohumoral centers are particularly sensitive to the inhibitory effect of circulating sex Steroids. As puberty is reached, this sensitivity decreases, resulting in the "activation" of the secretion of hypothalamic regulatory hormones.

Biogenic amines, particularly Neurotransmitters such as norepinephrine and dopamine, participate in hypothalamic-pituitary-gonadotropic regulation and secretion.

In boys, the peripubertal period (from 7 to 9 years) is characterized by the elongation of the testes. They acquire a cylindrical shape and can reach 2–4 cm in length, with an increase in diameter as well. The scrotum is smooth, lacking rugae. The penis enlarges slightly, with a length of approximately 3–5 cm. Pubic and axillary hair are absent, and there is no vellus body hair either. Increased body odor is not observed.

During the neopubertal period (ages 9–11), further testicular growth takes place, with length reaching 3.5–5 cm and a cylindrical shape. The length of the penis increases to 5–8 cm. As in previous stages, no significant enlargement of the prostate gland is observed. Increased body odor and voice mutation are noted. Folds and pigmentation begin to appear on the scrotum, and scrotal suspension is regulated primarily by ambient temperature. Axillary hair is absent, while pubic hair appears as a very fine down. Gynecomastia may develop during this time, caused by a slight accumulation of tissue approximately 1 cm thick and 1–2 cm in diameter directly beneath the areolae, accompanied by firmness and tenderness upon Palpation. Between the 8th and 12th years of life, boys experience lateral body growth, particularly in the chest, alongside muscular development.

During puberty (ages 10–14), further elongation of the penis and testes is observed (testicular length 4–6 cm, diameter 2–3 cm; penile length 6–9 cm), and spermatozoa begin to be produced within the seminiferous tubules. Pubic and axillary hair appear. As a rule, a beard is still absent, with only a fine down visible on the face, along with sparse body hair. Spontaneous or induced erections and pollutions are possible at this stage. Gynecomastia typically disappears, but may progress in cases of endocrine disorders (sometimes reaching the size of female breasts, a phenomenon also seen during the neopubertal period of female maturation). Between the 13th and 16th years, growth velocity increases, during which the laryngeal cartilages also undergo changes, leading to voice deepening.

In the postpubertal period (age 15 and older), a boy's height matches that of an adult. Growth of all body parts and the penis continues. Distinct folds and pigmentation appear on the scrotum, pubic and axillary hair grow, and facial hair emerges. Body odor becomes significantly stronger. The diameter of the testes exceeds 5–7 cm, and penile length reaches 8–12 cm. The prostate gland increases in volume, and its mucous secretion mixes with the seminal fluid, imparting its characteristic odor.

In girls during the parapubertal period (ages 1–8), the Mammary Glands are undeveloped, pubic and axillary hair are absent, and the pudendal cleft is immature.

During the peripubertal period (ages 8–11), the Development of the mammary glands begins: small tissue nodules appear beneath the unpigmented areola (about 2 cm in diameter). A fine down is noticeable on the Labia Majora, but pubic hair is absent. Body odor is imperceptible. The width of the pelvis increases, along with the subcutaneous fat layer, particularly in the pelvic, thigh, and gluteal regions.

In the neopubertal period (ages 10–12), further development of the mammary glands is noted as they extend beyond the edges of the areola; pigmentation is still absent. The size of the mammary glands is 3–8 cm in diameter, rising 2–4 cm above the chest wall. The first fine hairs are noticeable in the axillae and on the pubic area. Hair in the perineal region becomes denser, and body odor becomes perceptible.

Puberty (ages 11–14) is marked by the onset of menstruation, which is initially irregular and may be either ovulatory or anovulatory. The mammary glands measure 8–12 cm in diameter and rise 3–6 cm or more above the chest wall. The areolae are lightly pigmented. Axillary and pubic hair appear in a female distribution pattern. At this age, girls grow actively, with longitudinal growth predominating over transverse growth.

In the postpubertal period (ages 14–16 and older), the mammary glands of an adult woman are formed. Female-pattern hair distribution is characterized by relatively dense hair growth in the pubic and perineal regions. Vaginal mucus is secreted, and body odor is clearly distinguishable. Menstruation establishes regular or irregular intervals.

In the subsequent period of life, the organism attains biological maturity and becomes capable of reproduction. In adolescent males aged 16–17, a masculine physique is formed through robust muscular development and significant shoulder broadening, while beard growth begins around the 17th–18th year. In adolescent females aged 14–15, well-developed subcutaneous adipose tissue gives rise to characteristic female rounded body contours. With the onset of sexual maturation, ovarian dimensions increase, the uterine body elongates and thickens, and it acquires the shape and size of an adult Uterus. By the 16th–18th year, breast development is completed in girls, with the areola thickening like a disk, causing the nipple to protrude above it. At this age, both the female and male organisms are capable of reproduction. Sexual desire toward individuals of the opposite sex develops in both young men and women.

During the subsequent period of sexual maturation in both men (ages 18–34) and women (ages 17–28), Sexual Dimorphism reaches its maximum development. This is followed by the period of maturity (maturitas), toward the end of which primary signs of Aging appear. In senile age, a process of gradual involution takes place. First and foremost, it affects the Reproductive System and exhibits specific features in each sex. The Functions of the gonads exist in the closest interaction with the entire Endocrine System of the organism. Gonadal function is influenced by hormones from The Thyroid Gland, pituitary, Adrenal Glands, and other endocrine organs. Acting upon one another continuously—at times inhibiting, at times accelerating secretory functions—they form, together with the gonads, a system that performs vital functions extending far beyond purely sexual matters. "Only thanks to the Ovaries is a woman what she is"—this statement by R. Virchow was paraphrased by A. Biedl: "Through The activity of the Endocrine glands, man and woman are what they represent." This notion underscores The Importance of endocrine gland functions, which not only influence morphohormones but also interdependently regulate physiological and psychological processes within the organism. However, regardless of the action of Sex Hormones, it does not encompass all phenomena of physical and psychological dimorphism.