Sexual development is a process of physical and mental development and the occurrence of significant changes in the sexual system of the girl. Sex differentiation begins as early as the 7th week of gestation during the intrauterine life of the fetus, when the formation of the sexual organs begins. It is only during puberty that massive secretion of hormones from the gonads begins, which stimulates the development of secondary birthmarks. The periods through which the girl goes in her development are: Neonatal period – begins immediately after the birth of the child and lasts 2-3 weeks. Latent period – begins after the neonatal period and continues until the onset of puberty. Puberty period – starts from 9-10 years of age and lasts until about 18 years of age. The neonatal period is characterized by a high concentration of hormones – mainly estrogens, which have passed through the placenta during intrauterine development of the fetus, immediately after birth their level is increased. They gradually decrease over about 2-3 weeks. This condition is referred to as a “hormonal crisis” in the newborn. Under the action of sex hormones, specific features of the sexual organs are observed. When conducting a microbiological examination of vaginal discharge, the presence of a small amount of lactobacilli is found, the pH is about 5. The drop in hormones may be associated with the appearance of light bleeding through the vagina, the duration of which is about 4-5 days. Changes may also be found in the breasts of the newborn girl, they may be slightly enlarged and secrete a small amount of liquid that resembles colostrum. The latent period begins after the drop in the levels of hormones that have passed through the placenta into the fetus. The duration of this stage is strictly individual. Through it, the secretion of sex hormones is minimal. During this period, the vagina has a greatly reduced secretion, lactobacilli are absent. At the beginning, from the external genitalia, the presence of Staphylococcus epidermitis, which normally inhabits the skin, or bacteria characteristic of the gastrointestinal tract can be detected. The vaginal environment is alkaline. Puberty is divided into three stages – pre-puberty, puberty and post-puberty. The Tanner classification is used to determine the degree of development of secondary genital marks in the girl. It shows gradually through 5 stages the growth of the mammary glands – thelarche, the specific female genital hair – pubarche and the hair under the arms – axilarche. The term menarche refers to the girl’s first menstrual bleeding. NEWS_MORE_BOX The period before puberty proper begins with the development of the female genital organs. Under the action of the increased synthesis of sex hormones, growth of the vagina is observed, its length increases and its wall thickens. Again, lactobacilli are found in the vaginal discharge and they lead to the change of the environment to an acidic one. The uterus growsand in the ovaries, some of the follicles begin to pass into the stage of growing follicles. The development of the secondary sex marks – thelarche, pubarche and axilarche also begin their development and may reach the second or third degree. At the heart of the puberty stage is the onset of menarche. Reaching the first period is usually the result of a decline in sex hormones after their peak. Most often, the first menstrual bleeding is not preceded by ovulation and is therefore referred to as pseudomenstruation. The post-puberty period is characterized by the formation and development of secondary sexual characteristics in women. The period of development of sexual maturity, in addition to important changes in the organs, is also associated with mental changes and the emergence of sexuality in women. Thus, at the end of puberty, the female organism is fully developed to perform its reproductive functions. 3828