Female sexual organ development Female sexual organs include: uterus, ovaries, fallopian tubes, vagina and external genitalia. The uterus is divided into three parts: the cervix, the body and the fundus. If the ultrasound shows that the volume of the uterus is >2.5ml and the volume of the ovaries
>1ml, it indicates early pubertal development. The size of the ovaries at sexual maturity is approximately 4 cm x 3 cm x 1 cm. Male sexual organ development Male sexual organs include: testes, penis, scrotum, vas deferens and accessory glands. The Prader testicular model (a string of ovoid wooden models with volumes of 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 20 ml and 25 ml) is commonly used to clinically determine the degree of testicular development, and the number of milliliters of the model is the number of milliliters of testicles when the two match in size. Developmental sequence Female: breast enlargement – appearance of pubic and axillary hair – first menstruation. This period lasts 3 to 3.5 years (2 to 3 years for sudden height increase). Males: Enlargement of testicles – Enlargement of penis and scrotum – Appearance of pubic and axillary hair – Spermatorrhea, sperm maturation, simultaneous voice change and appearance of acne. This period lasts for 4 to 5 years (sudden height gain of about 3 years). Peak height growth Usually lasts 1 year. The average age of emergence for girls is 12 years, mostly in the B3 stage of breast development, 6 to 11 cm/year (average 9 cm/year). The average age of emergence in boys is 14 years, around the G4 stage. Peak height growth is more than 1 cm/year more than in girls (average 10 cm/year). Changes in body shape Due to hormonal changes in the body, the accelerated height growth during puberty is accompanied by changes in body shape. In boys, shoulder chondrocytes are sensitive to testosterone and produce a proliferative response, which manifests as a widening of the shoulder. In girls, pelvic chondrocytes respond prolifically to estrogen and widen the transverse pelvic diameter. The age of sudden increase in transverse pelvic diameter is 2 to 3 years before menarche, peaking one year later and slowing down and stopping rapidly at menarche. Before puberty, boys and girls have the same amount of body fat and lean body tissue. After puberty begins, as the androgens (especially testosterone) in boys ↑, promoting protein synthesis and bone salt deposition, while enhancing growth hormone synthesis and promoting fat decomposition, the amount of lean body increases significantly and body fat decreases, eventually forming the male body type with bone growth, thickening, large muscle mass and muscle strength, especially developed deltoid muscles. While girls under the action of estrogen, the whole body subcutaneous fat deposition increased, especially in the buttocks, chest and thighs, while the lean body volume increased slowly. At the same time, due to the widening of the transverse diameter of the pelvis, the formation of the characteristic female body shape. The development of puberty is a gradual process that lasts from 2 to 6 years, generally 3 to 3.5 years.