Men's Health Guide: Analysis of Sexual Maturation Stages and Intervention for Physiological Abnormalities

Male Sexual Maturity

Sexual maturity is the true maturity of a human being in a biological sense, marking the end of childhood. Only sexually mature individuals can assume the responsibility of procreation.

Sexual development includes the development of primary, secondary, and tertiary sexual characteristics. Primary sexual characteristics refer to the genetically determined differences in the structure of the male and female reproductive organs, manifested during the embryonic period and in newborns. Secondary sexual characteristics refer to the differences in physical features between the sexes, other than differences in reproductive organs. Tertiary sexual characteristics refer to the differences in behavior and personality between the sexes, specifically masculinization or feminization in behavior and personality. It should be noted that tertiary sexual characteristics are not as strictly defined as primary and secondary sexual characteristics. Some men may exhibit certain feminine traits, and some women may exhibit certain masculine traits; this phenomenon is often clearly correlated with hormone levels and social occupation.

Male sexual maturity begins with the maturation of the male reproductive organs, followed by the development of secondary sexual characteristics and the completion of masculinization (the development of tertiary sexual characteristics). Before puberty, the male reproductive organs show almost no morphological changes. In the pre-pubertal period, about one year before the sudden increase in height and the onset of penile growth, the testes begin to enlarge. Before development, the volume of the testes is only 1-3 ml. This increase in testicular volume reflects the transformation of the seminiferous tubules from narrow, indistinct cords into more curved tubules. Around age 10, spermatogonia in the seminiferous tubules begin to undergo mitosis, and it takes about three years for mature sperm to be produced. By the time the reproductive organs are fully developed, the volume of the testes will reach 12.5-20 ml. According to domestic reports, the normal testicular volume in Chinese men is slightly smaller than that in Western men. The large amount of androgens, primarily testosterone, secreted during testicular development stimulates the growth and development of the male accessory sex organs, namely the prostate, seminal vesicles, and epididymis, enabling them to function normally.

Nocturnal emission is a marker of male sexual development, but it cannot be used as a time marker for the stage of sexual development. Boys can experience penile erection in early infancy, but they only experience sexual pleasure for the first time during their first nocturnal emission. According to a survey conducted in Beijing in 1979-1980, the age of first nocturnal emission was 15-16 years old, and it mostly occurred in the summer.

The developmental sequence of male secondary sexual characteristics is as follows: gradual increase in testicular and penile size, appearance of pubic hair, onset of voice change, rapid growth of the Adam's apple, appearance of axillary hair, first nocturnal emission, and formation of facial hair. Simultaneously, this is accompanied by darkening of the areola and the appearance of a strong masculine odor.

Delayed and Inhibited Sexual Development

Delayed or inhibited sexual development refers to abnormal sexual development in which secondary sexual characteristics and reproductive organs remain in an immature state during puberty at the normal age of sexual development. Clinically, delayed or inhibited sexual development is generally diagnosed when females fail to develop breasts by age 14 and fail to experience a growth spurt by age 15; or when males fail to develop testes by age 14 and fail to experience a growth spurt by age 16.

Delayed and inhibited sexual development are two fundamentally different clinical types. Delayed sexual development is a delay in the developmental process in terms of age, but normal puberty can still occur at a certain age. Inhibited sexual development, on the other hand, involves the suppression of normal development, and puberty will not occur without treatment. Both delayed and inhibited sexual development occur more frequently in males. The physical and mental health of patients is also affected, and timely treatment is essential. It is generally believed that most cases of delayed sexual development are constitutional. Malnutrition, severe zinc deficiency, trauma, parasitic diseases, and many chronic diseases (congenital heart disease, anorexia nervosa) can all cause delayed sexual development. Other causes of delayed or suppressed sexual development include congenital ovarian or testicular hypoplasia, hypothalamic-pituitary damage, hypothyroidism, and chromosomal disorders.

The diagnosis of delayed or suppressed sexual development should be made as early as possible. Patients may face discrimination due to late maturation, leading to psychological stress. Constitutional delayed sexual development can often be improved by strengthening the body. If problems arise, consult a doctor promptly and avoid self-medication.

Precocious Puberty

Precocious puberty is a developmental abnormality characterized by the premature appearance of sexual maturity. It is a clinical manifestation of secondary sexual characteristics appearing earlier than the average age of sexual development in the general population. According to foreign reports, the incidence of precocious puberty in boys and girls is approximately 0.6%. The diagnostic criteria for precocious puberty mainly include the following:
① Breast enlargement before age 8.

② Pubic or axillary hair appearance before age 9.

③ Menstruation before age 10.

④ Male penile enlargement and female clitoral enlargement exceeding normal levels.

⑤ Premature appearance of other sexual development-related phenomena, such as voice change and facial hair growth.

Precocious puberty can be divided into true precocious puberty and pseudoprecocious puberty. The clinical manifestations of true precocious puberty are completely identical to normal sexual development, except that the age of sexual development is advanced. In these children, the hypothalamic-pituitary-gonadal axis is activated prematurely, increasing gonadotropin secretion and causing the appearance of secondary sexual characteristics. Male children may experience testicular and penile enlargement and sperm production. Female children may experience breast development and menstruation. True precocious puberty is mostly idiopathic, meaning that these children show no organic lesions upon clinical examination. However, a small number of children with precocious puberty are caused by neurological diseases, such as brain tumors, infections or granulomas, brain abscesses, and sarcoidosis, all of which can cause true precocious puberty. Although children with pseudoprecocious puberty exhibit some symptoms and signs of precocious puberty, their hypothalamic-pituitary-gonadal axis is not activated.

The premature development of sexual characteristics is generally believed to be related to excessive secretion of gonadotropins and autonomous androgens. Clinical studies have confirmed that in all male patients with pseudoprecocious puberty, FSH secretion is not activated, serum FSH levels are not elevated, and because the seminiferous tubules of the testes are not affected, there is no significant testicular enlargement.

Children with symptoms and signs of precocious puberty should promptly consult an endocrinologist for diagnosis and treatment. The specialist will determine whether treatment is necessary and how to proceed based on the patient's condition and clinical examination results.