Читать книгу Ridley's The Vulva - Группа авторов - Страница 123

Puberty is related to gonadal maturation and the sex hormones that they start to produce. The physical changes associated with puberty are breast development, appearance of axillary and pubic hair, and the onset of the menses. Puberty is also accompanied by an increased growth rate. The timing of puberty is influenced by environmental and genetic factors and by obesity. There are significant ethnic differences in the onset of puberty, with 48% of African American girls having some signs of puberty at age 8 as opposed to only 14% of Caucasians [25]. Girls who present early do need follow‐up to exclude precocious puberty.

The adrenal glands mature first, usually about two years before menarche. The ovaries enlarge with an increase in the number of growing follicles, although they subsequently regress. The average age of menarche varies considerably, but it is estimated that about 95% of adolescent females have their menarche between the ages of 11 and 15 years. Menarche usually occurs within 2 years of breast budding.

It is thought that the pilosebaceous units are present at birth but do not develop until activated by hormonal stimulation at puberty. The apocrine glands of the axilla and vulva begin to function at about the time that axillary and pubic hair appears, and the sebaceous glands at all body sites become more active. The development of puberty is described according to Tanner [26], and growth of pubic hair is described in five stages:

1 No pubic hair

2 Sparse hair on the labia majora and on the mons pubis in the midline

3 Increase in hair density and texture, especially on mons pubis

4 Further increase so that only the upper lateral corners of the usual triangular distribution are deficient

5 Normal adult pubic hair pattern with its extension from the labia on to the medial aspects of the thighs, this is usually completed between 12 and 17 years

In the vulva, fat deposition increases the size of the labia majora and the prominence of the mons pubis. The labial skin becomes rugose, the clitoris increases in size, and the urethral orifice becomes more obvious. Coincidentally, Bartholin’s glands become active, and the hymenal ring enlarges.

The development of the ovarian follicles is associated with increasing levels of oestrogen production, which is responsible for the thickening of the vaginal epithelium and the glycogenation of the cells. The vaginal secretions increase in quantity and become more acidic, with a pH of between 4 and 5.