Puberty

Puberty


INTRODUCTION:

  • Puberty is the period of transition from childhood to adult sexual maturation.
  • Process of biological, psychological and physical development through which sexual reproduction becomes possible
  • Thelarche → Adrenarche → Peak growth spurt→ Menarche→ Ovulation
  • Age of onset of puberty: Varies between 9 and 13 years & lasts 2–3 years
  • The difference in the age of onset of puberty amongst males may be explained by Increased Inhibin levels

Endocrine mechanisms underlying puberty:

  • Early in puberty: Sensitivity of the gonadostat to the negative effects of low estradiol decreases.
  • Late in puberty: Maturation of positive E2 feedback initiates the LH surge.
  • Basal levels of pituitary gonadotropins increase throughout puberty 
  • Estrogen  is mainly responsible for skeletal maturation of long bones during puberty
  • 35 gms  is the approximate weight of thymus gland at puberty
  • Hormones required during puberty are LSH, Testesterone & Leptin

Factors Affecting Time of Onset:

  • Genetics
  • Race.
  • Nutritional status
  • General health status
  • Altitude
  • Psychological state
  • Exposure to light

STAGES:

Tunner and Marshall described five stages of pubertal changes:

  • Physical growth and weight gain
  • Development of breasts
  • Pubic and axillary hair
  • Development of ovaries and genital organs
  • Growth of sport and menstruation

Thelarche:

  • First sign of puberty is the development of the breasts.
  • Breast budding:9–11 years
  • Indicative of the competency of the hypothalamic– pituitary–ovarian axis.
  • The adolescent breast development is divided into 5 stages:
Stages Features
B1
  • Prepubertal breast
  • Papilla is elevated
B2
  • Denotes thelarche
  • Breast buds are palpable,
  • Areola enlarges
  • Breast is elevated like a small mound.
B3 Enlargement of breast and its areola without separation of its contours.
B4 Formation of a secondary mound over the mound of the breast.
B5 Mature adult breast

Adrenarche:

  • The adrenals are the main source of androgens
  • Responsible for the growth of pubic and axillary hair
  • First sign of puberty in female Tanner stage II

Pubic Hair Development:

Stages Features
P1
  • Prepubertal 
  • No coarse pubic hair

 

P2
  • Denotes pubarche
  • Long or slightly curved and pigmented hair sparsely over the labia.
P3
  • Darker, coarser and curly hair over mons pubis
P4
  • Preadult stage
  • Area short of the inverted triangle
P5
  • Adult inverted triangular distribution
  • Thick, coarse, dark curly hair spreading out towards the medial aspects of the thighs is evident

Axillary Hair Development:

Stages Features
A1
  • Prepubertal 
  • No axillary hair
A2
  • Appearance of sparse axillary hair.
A3
  • Thick, coarse and dark pigmented hair

Genital Organs:

  • Vulva:Vaginal mucosa becomes multilayered
  • vulval skin keratinized and resistant to infection.
  • Fat is deposited in the labia majora.
  • The uterus grows rapidly, and prepubertal ratio of uterus/cervix of 1:1 changes to 2:1 or 3:1.
  • The ovaries start developing primordial follicles into Graafian follicles

Menarche:

  • The initial menstrual cycles are generally anovulatory for about 12–18 months after menarche
  • Follows thelarche by about 2 years
Exam Question
 
  • Orchidopexy for cryptorchidism is done at the age of Puberty
  • 2:1 is the ratio of length of cervix and body of the uterus before puberty 
  • According to Tanner stages of development, Thelarche is the first sign of puberty in females
  • The first sign of puberty in girls is Breast budding
  • 35 gms  is the approximate weight of thymus gland at puberty
  • The difference in the age of onset of puberty amongst males may be explained by Increased Inhibin levels
  • Estrogen  is mainly responsible for skeletal maturation of long bones during puberty
  • Gamma amino butyric acid (GABA) has an inhibitory control over the GnRH neurons before the onset of puberty
  • Thelarche-puberche-growth spurt-menarche is the correct order of events at puberty in a girl
  • Hormones required during puberty are LSH, Testesterone & Leptin
  • First sign of puberty in female Tanner stage II
  • Sign of puberty in boys is Enlargement of testes
Don’t Forget to Solve all the previous Year Question asked on Puberty

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