Sexual maturation is a period in human development in which hormonal and somatic changes take place, leading to sexual maturity and reproductive capacity.
In clinical practice, this means: development of secondary sexual characteristics, acceleration of growth (pubertal growth spike) and changes in body composition usually occurring between 8 and 18 years of age. Somatic changes in adolescence are accompanied by changes in the behavior and psyche of the child.
In the course of puberty, the secretion of a number of hormones increases:
gonadoliberin (GnRH) through the hypothalamus (in a pulsating manner)
gonadotropin – lutropin (LH) and follitropin (FSH) through the pituitary gland,
sex steroids – estrogen and testosterone through the gonads,
adrenal androgens – dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEAS) through the adrenal cortex,
growth hormone (GH), insulin-like growth factor I (IGF-I), insulin.
The phase of proper sexual maturation – gonadarche – may begin at the age of 8 in girls and 9 in boys. It is preceded by the adrenal phase – adrenarche, which is characterized by the development of pubic and axillary hair, as well as acne and seborrhea. The maturation stages are assessed on a scale developed by Tanner and Marshall. There are five stages in the development of pubic hair (pubarche), five stages in the development of the mammary glands (thelarche) and five stages in the development of the genital organs in boys.
A 3- or 4-grade scale is used to assess the development of axillary hair.
In girls, the first symptom of puberty is usually the development of the breast glands (thelarche). Another sign of puberty is the development of pubic hair. It depends mainly on the secretion of androgens by the adrenal glands and ovaries. In the course of sexual maturation, the size and shape of the uterus also change. The ratio of the body length to the length of the cervix increases. The ovaries also expand from less than 1 ml in pre-puberty to 10 ml. The first menstruation (menarche) occurs on average 2 years after thelarche (mean age 12,7).
Maturation is quite slow at first; in the third stage it is accelerated – then there is also a pubertal growth spike. The Tanner maturation stages and hormonal changes in their course in girls are presented in Table 14.1.
The first symptoms of puberty in boys appear between the ages of 9 and 14, on average at the age of 11,5. The first sign of the onset of puberty is usually an increase in the size of the testicles over 2,5 cm in the longest dimension, which corresponds to a volume of 4 ml. Pubic hair begins initially at the base of the penis (usually 6 months after testicular enlargement) and gradually spreads over the scrotum and the white line, reaching the navel. Penile growth is another symptom of maturation and appears on average 1-1,5 years after testicular enlargement. The pubertal growth spike in boys occurs at an advanced stage of puberty. The presence of sperm in the morning urine (spermarche) occurs after reaching the bone age of 13,5 years.
Boys usually reach full sexual maturity between 13 and 18 years of age, while the speed of growth is highest at the average age of 14. The Tanner stages of puberty and hormonal changes in their course in boys are presented in Table 14.2.
Source: A. Cajdler-Łuba, S. Mikosiński, A. Sobieszczańska-Jabłońska, I. Nadel, I. Salata, A. Lewiński: “FUNCTIONAL DIAGNOSTICS OF HORMONAL DISORDERS WITH ELEMENTS OF DIFFERENTIAL DIAGNOSTICS; Czelej Publishing House